Chemistry

SCIENCE
Teacher Instruction Manual
Chemistry & Physics
Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Grade 10
2007

Department of Science, Health & Physical Education
Faculty of Science &Technology
National Institute of Education

Science
Grade 10
Chemistry & Physics
2007

© National Institute of Education

ISBN-

Department of Science, Health & Physical Education,
Faculty of Science &Technology,
National Institute of Education.

Printing:
NIE Press,
National Institute of Education,
Maharagama.

i

Message of the Director General

The first curriculum revision for the new millennium is based on the elimination of the several
problems obtaining in the present education system. The present curriculum reforms have been
planned having identified the problems that youth face consequent to the weakening of their
thinking abilities, social abilities as well as personal abilities and step by step exploration of
factors leading to this situation, to overcome which, the necessary background was prepared.

Compared to the other countries in the Asian region, our country took the lead in education in
earlier years. But most countries in this region have superceded Sri Lanka in education today.
Some factors that influenced this deterioration are the action taken by educational institutions to
continue to take action to confirm the known, learn that which had been decided on earlier, and
reconstruct that which was, in the same form itself.

All these matters have been taken into consideration and the officers of the National Institute of
Education have endeavoured to prepare the new curriculum on the basis of a distinct philosophy.
The primary objective here is to change that which is known, explore that which is new and
develop that which is necessary for tomorrow and build up a generation of students who can
display their readiness for a successful future. But there is no need to reiterate, the need for a
visible change in the teacher’s role for the realization of this objective. In place of the obvious
transactional teacher role presenting in our classrooms so far, the Sri Lankan school teacher will
have to understand and conform to a student-centered, competency based and activity focused
transformational role.

It is our firm belief that this Teacher Instruction Manual will serve you as an aid to become an
effective teacher through the provision of numerous instructions that will help you adapt to the
new situation. Through the study of these instructions you will be provided the opportunity of
making your daily teaching as well as the evaluation task easy. There is no doubt that instructions
for student exploration and other quality inputs will help facilitate the teacher’s task. Similarly,
the Teacher Instruction Manual will help convey to school principals valuable information they
can use in time-tabling, sharing of limited resources and internal supervision.

My sincere thanks go to Dr. Mrs. I. L. Ginige, Assistant Director General (Curriculum
Development) Science & Technology Faculty of National Institute of Education for her direct
involvement in the preparation of this Teacher Instruction Manual that will serve an immense
purpose in the task performed at school level by the section above and also teacher educationist
involved in beginning or continuous teacher educational matters, in-service advisors as well as
officers at various levels, involved in external supervision plus monitoring programmes.

Professor J. W. Wickramasinghe
Director General
iii

Preface
The first curriculum reform for the millennium implemented with the aim of preparing a
powerful basis for a new Sri Lanka anticipates a visible transformation of the teacher’s role. The
three main sections below are included in the Teacher Instruction Manual prepared with the
objective of providing the teacher with the necessary support in this regard.

· Detailed Syllabus
· Activity Continuum that helps in the implementation of the syllabus
· Instruments for the extension of the learning teaching process.
Teachers have been provided the opportunity of understanding several basic matters that
have been taken into consideration in the preparation of the curriculum for the detailed syllabus
extending beyond subject topics and sub-topics. Competency levels that correspond to subject
competency have been included in this section that commences with an introduction to the factors
and subject aims that formed the basis of the new syllabus. One special features of this section is
that, while the knowledge-base determined under competency level each student needs to develop
has been introduced as the subject content the multiple learning and teaching methods employed
in transmitting this section to the student has also been taken into consideration in determining the
time frame with respect to each competency level.
The final part of the detailed syllabus presented under the heading “School Policy and Programs”
needs to be studied very carefully and understood by every instructional leader. This section
provides school managers a range of valuable instructions to assist them in the allocation for
teaching, subject-teaching assigning functions to teachers, implementing co-curricular activities
as well as supervision of the teacher’s task. The second section of the Teacher Instruction Manual
has been prepared with the objective of providing teachers with clear understanding of the proposed
learning- teaching methodology. This section commences with the introduction of the methods of
planning activities under competency-based education as well as the change in the teacher’s role.
Although the activity continuum necessary for the implementation of the curriculum has been
introduced next, the implementation of the proposed activity in the very same manner is not
expected of teachers. The teacher should endeavor to make use of his / her creative, as well as
critical thinking abilities and adapt these activities in a manner that suits ones class, best. Although
instructions have been provided on the constitution of groups in keeping with the facets of the
problems subject to exploration, the teacher is expected to take an intelligent decision on the
number of groups based on number of students in the class.

iv

Time has been allocated for activities to ensure achievement of the relevant competency levels.
Therefore, teachers may have to exceed the 40-minute period. While each activity has been
provided adequate time for the actualization of each competency level, the teacher is expected
to make use of single or double periods in the time table and breakdown these activities, as
suitable in implementing them.
For the success of the procedure it is essential that every time an activity commenced the previous
day is carried over to the following day, that a brief summary of the part of the activity completed
the previous day is presented to the class. Similarly, this decision will provide the school community
with the opportunity of involving students in effective learning where teachers obtain leave of
absence.
The final item in this section is a list of quality inputs necessary for the maintenance of the quality
of subject learning and teaching, when taken as a whole. As such, the teacher has a choice of
ordering out the necessary learning-teaching materials in time and having them on hard.

Included in the third part of the teacher Instruction Manual under the title
“ Assessment and evaluation” are a number of important hints to ensure that the expected results
of the exercise are realized.

This section has been so structured as to introduce matters related to the assessment and evaluation
that should take place under each activity, extension of the learning and teaching that takes place
based on activity groups and the nature of the questions that might be expected in general
examinations. It must be pointed out that the primary responsibility of the teachers is to Identify
instances where assessment and evaluation can be implemented in the course of each activity
and to carry out this task successfully on the basis of common criteria. The set of instruments
prepared with a range of activities as the objective for the purpose of extending learning and
teaching provide students with the opportunity of involvement in continuous learning outside the
recommended classroom sessions. While it is the task of the teacher to regularly examine the
learning students receive, based on these instruments, and encourage them, arriving at a correct
decision regarding the final results of the activities and communicating that decision to the relevant
parties is expected of the teacher. It is essential that a visible change takes place in general
examinations for the success of the learning-teaching process. The National Institute of Education,
with the assistance of the Sri-Lanka Department of Examinations, has introduced several prototype
questions for educational levels that terminate with these examinations. Since this change in
examination question papers has been suggested in order to direct students to learn through
practice and experience, instead of resorting to mechanical approaches like memorizing or
answering model question papers, the education of school students and parents about this change
should commence at the beginning itself.
v

All teachers should realize that various activities can be developed for the achievement of any
particular competency level. Accordingly, they should be prepared for more successful teaching
through the use of better approaches, exploration, as well as instruments for the extension of
learning and teaching.
The present Teacher Instruction Manual will give teachers right throughout the country the courage
to effect a visible change in the teacher’s role and prevent their becoming inactive in the presence
of new approaches. Similarly, we expect to award certificates and provide numerous development
opportunities to teachers who go beyond the activities to involve themselves in the innovation of
novel creations. What teachers have to do order in to become eligible to the awards is to improve
these activities, using their creative thinking, and present them. Learning-teaching plans prepared
in this manner outside the basic activity plan, should be forwarded to Assistant Director General
( Curriculum Development ), Science and Technology faculty, National Institute of Education,
Sri Lanka. Selection of those entitled to awards will be made subsequent to the study of these
activities by the relevant subject committees.
We have endeavoured in this manner, to bring learning-teaching assessment and evaluation on to
the same platform through new methodologies. According to this, teachers will be provided
substantial latitude to meaningfully handle the learning-teaching process, school-based assessment,
as well as assignment of home-work. It is our firm conviction that the school system of Sri Lanka
will, make maximum use of this aid and depart from orthodox learning-teaching approaches to
enhance the thinking abilities, social abilities as well as the individual abilities of the sons and
daughters of the county.

Dr. Indira Lilamani Ginige
Assistant Director General (Curriculum Development),
Faculty of Science and Technology ,
National Institute of Education,
Sri Lanka.

vi

Direction: Prof. J W Wickremasinghe - Director General

Guidance: Dr. I. L. Ginige
Assistant Director General
Faculty of Science and Technology

Supervision : Mr. C M R Anthony
Director
Department of Science, Health & Physical Education

Instructional leadership, Co-ordination and Editing :
Mr. C M R Anthony - Director
Mr. G H Gauthamadasa - Chief Project Officer
Mr. W A D Rathnasuriya - Chief Project Officer
Mr. W A Sumathipala - Project Officer
Ms.J Athamlebbe - Project Officer
Mr. A D A de Silva - Project Officer
Mr. L K Waduge - Project Officer
Mr. P Malavipathirana - Project Officer
Ms. Nadee Ama Jayasekera - Project Officer
Ms. H M Mapagunaratne - Asst. Project Officer

Translation : Mr. R.B.A.Jayasekara
Computer page setting : Mr. K.Wimalasena, Mahinda College, Galle.
Art : Ms. U L N Fernando
Teacher Service,
Sirimavo Bandaranayake BV. Colombo.07.
Cover page and pictures : Master. Soraj Dhananjaya Kolonne,
Grade 11, Thurstan College, Colombo.

vii

Contents

Page
² Director General’s Message iii

² Preface iv

² Contributors vi

² Contents vii

² School Policies and Progammes 15

· Learning-Teaching Methodology

² Introduction 18-20

² Quality Inputs 21

² Activity Continuum 22-114

· Assessment and Evaluation

² Introduction 117-118

² Tools for Extended Learning 119 -124

² Prototype Questions 125 -129

viii

Competency 1.0 ( Investigates Scientific findings about
structure of matter and quantity

Competency level 1.1( Discuss the scientific findings about the structure of
atom.
Activity 1.1 ( Let us go inside the atom.
Time ( 120 minutes
Quality inputs ( ² Photograph of a nuclear reactor.annex 1.1.1
² Three copies of instructions for exploration given in
annex 1.1.2
• ² Three copies of the article"Let us get inside

the atom"annex 1.1.3
² Demy papers and pastels
Teaching-learning process (
Step 1.1.1 ( ² Display the photograph to the class.
² Inquire from the children as to what know about what is
given in the picture
² Conduct a brain storming discussion to highlight the
following.
That,
² In an atomic reactor,the energy in the atoms is
transformed into energy that is useful to man.
² atom is the building blocks of matter.
² The findings about the atom can be made use of for the
benefit of man.
(15 minutes)
Step 1.1.2 ( ² Divide the class into three groups.
² Provide the groups with copies of instructions for
exploration.
² Assign the tasks and engage the groups in exploration.
² Prepare them to present their findings to the class.
(60 minutes)
Step 1.1.3 ( ² Get each group to present their findings to the class.
² Give the first opportunity to the respective group to
elaborate on the presentation.
² Get the other groups to propose constructive sugges
tions,
² Elaborate highlighting the following points.

9

That,
² Atom is a particle with a small mass.
² Fundamental sub atomic paticles inclued in an atom
are electrons,protons and neutrons.
² Out of the paticles the lightest particle is the
electron.
² mass of an electron is about 9.1095x 10-31 kg
² electron is a particle with a negative charge.
² Scientists J.J Thompson,Millikan Cotributed to the
fundamental studies about the electron .
² Proton is a partical having a mass of about 1840

times the mass of an electron.
² Mass of a proton is about 1.6725x10-31kg
² Proton is a particle with a positive charge.
² Proton is symbolised as 11p
² Ernest Rutherford contributed to the fundamental
studies about the proton.
² Neutron is a partical which has a mass almost equal
to that of a proton.
² Mass of a neutron is about 1.6750x10-20 kg.
² Neutron is a particle with no charge,it is neutral.
² Neutron is symbolised as 10n
² The number of electron or the number of protons in
an atom of an element is identical to that element.
² According to J.J Thompasons"Plum pudding "model
he stated that an atom is a sphere which is positively
charged,and the electrons which are negatively
charged are embeded in it.
² According to Rutherford solar model the protons,and
neutrons are collected at the centre which is the
nucleus and the electrons are moving in orbits around
it.
² These shells are named as K.L.M.N from centre
out wards

(45 mts)

10

Criteria for assessment and evaluation
² Names and describe the fundamental sub atomic particles.
² Appreciates that scientists have contributed to the findings about the atomic structure.
² Compare different atomic models.
² Collect data about scientific discoveries using references.
² Present fact in an alternative way.
Annex 1.1.1

a

11

Annex 1.1.2
Instructions for group exploration
² Given below are three types of sub atomic particles in an atom.
² Electron
² Proton
² Neutron
² Focus your attention on the sub atomic particle relevant to you.
² With reference to the reading material provided to you discuss the follwing about the sub
atomic particle relevant toyou.
² It`s discovery

² Properties
² How it is placed in the atom according to different atomic models.
² Be prepared to present your findings to the class.
Annex 1.1.3
Let us go inside the atom
Atom is derived from the Greek word "atomos" which means ,not divisible further
but later it was discovered that it is made up sub atomic particles.Although there are many Sub
atomic particles only three important particles are mentioned below.
1& Electron
In the middle of the nineteenth century Scientists drew their attention whether
it is possible to conduct through gases
In 1875 B.C Crooks observed that in a closed glass tube with ends having two
electrodes and a high voltage is applied and in the meantime the air pressure inside to tube is
gradually reduced,there is a glow near the cathode.Further he noticed that if the air pressure is
further reduced this glow gradually move from the cathode towards the anode,and that there is
a"shadow" between the cathode and the anode.When the pressure inside the tube is about 1
pascall he noticed that the shadow got distributed throughout the tube and that there is an
emission of a beam of rays from the cathode to the anode.Since these rays were emitted from
the cathode they were named as cathode rays by crooks.This set up is called the cathode ray
tube.
In (1858BC-1940BC) J.J.Thompson conducted further experiments with these
rays,As a result of these experiments following conclusions were arrived at about the prop-
erties of cathode rays.

1 Cathode rays move in straight lines.
2 They are negatively charged
3 They are made up of particles having a mass.

12

J.J.Thompson conducted an experiment to determine the (e/m ) ratio of the cathode ray
particales, where (e) is the charge and (m) is the mass.
The value he got for e/m was very large
e/m=1.76x10 c kg-1
The values obtained for e/m ratio for the cathode rays using different gases and different cath-
odes is the same.By this Thompson concluded that the cathode rays consists of the same
particles.Further Thompson stated that,the fundamental unit of electricity,the electron introduced
by J.J. Stony in 1874 B.C.is the negatively charge particles in the cathode rays.
Electron is a common sub atomic particle present in all atoms.
Charge of an electron = 1.602x10-19 C
Mass of an electron = 9.1095x10-31 kg
At present different forms of cathode ray tubes are used in various electronic instruments.
Some of these are TV photo tube,Computer monitor,Cathode ray Oscilloscope,

Fluorescent tube

High Voltage

Cathode Anode

To Vaccum Pump

Simple Cathode Ray Emitting Tube

Proton

In 1886 B.C. E.Goldstien observed that when using a porous Cathode,is subjected to a voltage
from 20,000V to 50,000V some special rays were seen to emit from the pores in the Cathode in
a direction opposite to the Cathode rays.He named them as positive rays.
When ratio e/m was calculated for the particles in these positive rays it was found that the value
is numerically smaller to that of the particles in the cathode rays.

When different gases were used in the Cathode ray tube the e/m ratio for the particles in the
possitive rays were found to be whole numerical multiples of the e/m ratio for the particles in the
possitive rays.When Hydrogen gas is used in the cathode ray tube.In short the lightest possitive
rays particles were obtained from Hydrogen.In 1871 B.C-!937B.C Rutherford,named this lightest
possitive ray particle as proton and also that it should be the common possitively charged funda-
mental particle of all matter.
Charge of a proton=1.602x10-19C
Mass of a proton=1.6726x10-27 Kg
Mass of a proton is 1840 times the mass of an electron.
13

High Voltage

Anode
Cathode with a slit
production of possitive rays

Neutron

Possitively charged particles named α particles are emitted from radio active sources.When
fall on to the instrument to detect charged particals, it causes a deflection.(Fig. a)
In 1932 James Chadwick conducted an experiment form which it was founded that when a
thin Berylium sheet was place in between the radio active source and the detector no deflection
was seen ( Fig. b)
When a paraffin sheet was place between the Berylium sheet and the detector tere was a
α
deflection. (Fig. c)
Source of
Detector
particals
Shows deflection
(a) Possitive charge
particals fall on
detector
Berylium plate
No deflection is
shown
(b)
charged particals are
not falling on the
Berylium plate Paraffin wax plate detector
Shows a deflection
(c) charged particals
fall on the detector

particals Chargeless Neutrons Particals with possitive charge

(d)

14

Chadwick showed that when α Particles strikes the beryllium sheet it releases particles which
has no charge.When these particles strikes the paraffin sheet,it releases charged particles and
as a result there is a deflection in the detector.(Figd)

He also found that when particles strikes the beryllium sheet,the uncharged particles emitted
from it has a mass equal to that of the Hydrogen atom. He stated that these particles are another
type of sub atomic particles and named them as neutrons.
mass of a neutron = 1.6750x10-27 kg

Thompsons` Atomic Model(Plum pudding model)

α

Rutherford`s model of the atom(Solar model)

s Using rays emitted by radioactive material,in 1911 Geiger and Marsden conducted an
experiment to find the στρucture of matter under the direction of Rutheford.Here a beam of
particles was obtained using radio active polonium kept in a lead chamber with a slit.In this
experiment a thin gold foil was bombarded with particles.They kept a screen painted with Zinc
sulphide to detect the direction in which the particles move.There was a glow when
particles struck the Zinc sulphide sheet.
Rutherford's gold leaf experiment
Source of Polonium

Zinc Sulphide
screen which
could move
around the
gold leaf
Thin gold leaf
Led block with the hole

15

In this experiment it was discovered that most of the Alpha particals went through the gold foil
without any deviation, a small number of Alpha particals deviated when going through the gold
foil and a very small number were reflected. The reason why most of the Alpha particals went
through without any difficulty was because according to Rutherford a major part of an atom is
empty space.

Atom

α particals Nucleis

particals not diverging

Reflected particals particals diverging

Model to explain the results of Rutherfords experiment

α
Further according to Rutherford possitively charged particles some deviated and some reflected
because there are small areas inside atom where possitive charges are collected together.These
possitively charged areas he called nucleui.Later Rutherford Put forward a theory according
which he says,electrons are revolving in circular orbits around the nucleus,like the planets are
revolving round the sun.

electron

nucleus

path

16

Competency 1.0 ( Investigates Scientific findings about
structure of matter and quantity

Competency level 1.2 ( Use Scientific Conventions to highlight diversity in
atoms
Activity 1.2 ( Let us Investigates about atoms, make models, study about
diversity.
Time ( 120 minutes
Quality inputs ( ² Poster showing the planetary modle structure of Helium
and Sodium included in annex 1.2.1
² Four copies of instructions for exploration given in

annex 1.1.2
² Four copies of the article"Looking at an atom with an
exploratory eye", included in annex 1.2.3
² Beads of three colours or small rigifoam balls.,bucket
wires,gum,ekle and thread
Step 1.21 ( ² Display to the class the poster showing the structure of
Helium and Sodium atoms.
² Conduct a brain storming session to highlight the
following.facts.
That,
² The shells in an atom from nucleus outwards are named
K, L, M, N
² Helium atom has two electrons in the K shell
Sodium atom has K, L, M, Shells with 2,8,1 electrons
respectively.
• ² The highest number of electrons K,L,M,N shells could
have is 2, 8, 8,18
² The arrangement of electrons in the shells around the nucleus
of an atom is called electronic configuration
² The electronic configuration of an atom is one
convention which indicate the identify of an atom.
(15 minutes)

17

² Provide the class with copies of instructions for
exploration.material for making models,the letter,demy
paper and pastel
(60 minutes)
tions,

That,
² In Chemistry there are 110 elements discovered at
present.
² Every elements is symbolized using the letters in the
English Alphabet.

² Atomic number is the number of protons in the
nucleus of the atom.

² In a neutral atom the number of electrons(-
charges)and the number of protons (+chargs) are
equal.
² In the atomic nucleus both types of sub atomic
particles,protons and neutrons are present.
² In an element the number of protons is constant. But
there are atoms with varying number of neutrons.
² The total number of Protons and neutrons in the
nucleus of the atom is called the mass number or the
number of nucleons.
² Atoms of an element having identical number of
protons but different number of neutrons the mass
number varies.These atoms are called isotopes.
² In a chemical symbol of an atom on the top left side is
the mass number and at bottom is the atomic
number. ( 12C )
6

² The relative mass of an atom is the number of times
the mass of the atom relative to 1/12 of the mass of
12
6C
isotope atom.

18

² Relative atomic mass=mass of an atom of an element/massof
12
6C
isotope atomx 1/12
(45 minuts)

Criteria for assessment and Evaluation
² Names and describe conventions related to identification of elements.
² Appreciates that diversity of matter is built on diversity of atoms.
² Contruct models to show the structure of atoms.
² Show diversity by using Symbols.
² Discover facts using various Sources.

Arrangement of sub - Atomic particals in Helium and Sodium
He Atom
²
K Shell Electronic configuration 2
²

Na Atom

² K Shell
²²
²
² ²
²
L Shell
² M Shell
²
²² Electronic configuration 2" 8" 1

19

Annex 1.2.2


² Focus your attention to the six atoms assigned to your group, according to the table given
below.
Data of some atoms

Symbol A B C D E F G H I J K L MNO P QR S T UV WX
(not the
standard )
Number of
Protons 1 4 1 12 17 19 2 6 7 13 6 18 3 8 11 8 15 20 5 9 10 14 10 16

Number of 1 4 1 12 17 19 2 6 7 13 6 18 3 8 11 8 15 20 5 9 10 14 10 16
Electrons

Number of 1 5 2 12 18 20 2 6 7 14 7 22 4 8 12 9 16 20 6 10 10 1412 16
Neutrons

Group i Group ii Group iii Group iv

² Using data given in the table and the artical " Looking at the atom with an exploratory eye"
find the standard chemical symbols to the elements provided to you.
² Find the atomic mass and mass number of the atoms provided to you by using the types of
sub atomic particals and their numbers.
² Develope the eletronic configuration of the respective elements by writing the number of
eletrons in the cells from closer to the nucleus outwards.
² Develope using the letter discuss about isotopes and relative atomic mass and find out the
facts.
² Select necessary item from the common table and construct solar models of atoms allocated
to you.
² Be prepared to present constructions and findings to the class.

20

Annex 1.2.3

"Looking at an atom with an exploratory eye"

Do you know that all matter solids, liquids and gases found in your environment is formed by
110 elements getting grouped together in different ways ?
Each of these elements are formed from building units called atoms.Although it is not possible to
look at an Atom or its interior using the naked eye, the way the scientists by performing varius
experiments have been able to learn about the structure of these is amazing. To begin with let us
find about the sub atomic particals of atoms.

Sub Atomic Particals

Element Symbol Number of Number of Num,ber of

Electrons Protons Neutrons

Hydrogen H 1 1 --
Helium He 2 2 2
Lithium Li 3 3 4
Berelium Be 4 4 5
Boron B 5 5 6
Carbon C 6 6 6
Nitrogen N 7 7 7
Oxygen O 8 8 8
Fluorine F 9 9 10
Neon Ne 10 10 10
Sodium Na 11 11 12
Magnesium Mg 12 12 12
Aluminium Al 13 13 14
Silicon Si 14 14 14
Phosparous P 15 15 15
Sulphur S 16 16 16
Chlorine Cl 17 17 18
Argon Ar 18 18 22
Potasium K 19 19 20
Calcium Ca 20 20 20

Every element has a chemical symbol denoted by letters in the English alphabet. For easy study
it is possible to arrange the number of ptotons in the atomic nucleus of all the elements found in
the world. Now let us find out some theories about atoms.

21

Data of Elements of atomic numbers 1 - 20

Number of Electrons in the
Name of Chemical Atomoc shells Mass Relative
Element Symbol Number (Electronic configuration) number Atomic
mass
K L M N
Hydrogen H 1 1 1 1
Helium He 2 2 4 4

Lithium Li 3 2 1 7 6'9
Beralium Be 4 2 2 9 9
Boron B 5 2 3 11 10'8
Carbon C 6 2 4 12 12
Nitrogen N 7 2 5 14 14
Oxygen O 8 2 6 16 16
Fluvorin F 9 2 7 19 19
Neon Ne 10 2 8 20 20'2
Sodium Na 11 2 8 1 23 23
Magnisium Mg 12 2 8 2 24 24'3
Aluminium Al 13 2 8 3 27 27
Silicon Si 14 2 8 4 28 28'1
Phosporus P 15 2 8 5 31 31
Sulphur S 16 2 8 6 32 32'1
Clorine Cl 17 2 8 7 35 35'5
Argon Ar 18 2 8 8 40 40
Potasium K 19 2 8 8 1 39 39'1
Calsium Ca 20 2 8 8 2 40 40'1

22

Atomic Number
The atomic number of an element is the number of protons in the atom of that element.(In a
neutral atom the number of protons in the nucleus is equal to the number of electrons in the
shells.)

Mass number
The mass number of an element is the sum of the protons and neutrons in the atomic nucleus
of that element,

Relative atomic Mass
You could understand that atoms are particles having a very small mass hence it is not useful
in Chemistry to use the international unit of mass,the kilogram in relation to the mass of an
atom. Hence the mass of an atom is stated as a relative value of a standard unit.It is called the
Relative atomic mass unit.
12
Relative atomic mass Unit = mass of 6 C Isotope atom
12

The relative atomic mass of an atom is the number of times the mass of that atom in relation to
the relative atomic mass unit.It could be stated as

Relative atomic mass = mass of an atom
atomic mass unit
Relative atomic mass = mass of an atom of an element
12
mass of an atom of 6 C isotope x 1/12

There are differences between the atoms of the same element.An example of this is the presence
of atoms of elements with same number of protons but with different number of neutrons,Such
elements where the number of protons in the atomic nucleus is the same but the number of
neutrons vary,and as a result they vary in their mass number.These are called isotopes.

A Symbol is used to identify an atom.In an atomic symbol at the top left is the mass number
12
and at the bottom is the atomic number( 6 C)

23

Annex 1.2.6
Data about some of the isotopes found in nature of some elements

Name of Atomic Mass Symbol of Number of Number of Number of
element number number the isotope protons Neutrons Electrons
in the in the in the
nucleus nucleus nucleus
Hydrogen 1 1 1
H 1 0 1
1

1 2 2
1 H 1 1 1
1 3 3
1 H 1 2 1

3
Helium 2 3 2 He 2 1 2
2 4 4
2 He 2 2 2

Lithium 3 6 6
3 Li 3 3 3
3 7 7
Li 3 4 3
3

10
Boron 5 10 5 B 5 5 5
5 11 11
5 B 5 6 5

Carbon 6 12 12
6 C 6 6 6
6 13 13
C 6 7 6
6

14
Nitrogen 7 14 7 N 7 7 7
7 15 15
7 N 7 8 7

16
Oxygen 8 16 8 O 8 8 8
17
8 17 8 O 8 9 8
8 18 18
8 O 8 10 8

20
Neon 10 20 10 Ne 10 10 10
21
10 22 10 Ne 10 11 10
10 22 22
10 Ne 10 12 10

Sulpher 16 32 32
S 16 16 16
16
16 33 33
S 16 17 16
16
16 34 34
S 16 18 16
16

24

Chlorine 17 35 35
Cl 17 18 17
17
17 37 37
Cl 17 20 17
17

39
Potasium 19 39 19 K 19 20 19
19 40 40
19 K 19 21 19
19 41 41
19 K 19 22 19

40
20 40 Ca 20 20 20
Calcium 20
42
20 42 20 Ca 20 22 20
43
20 43 20 Ca 20 23 20
44
20 44 20 Ca 20 24 20
46
20 46 20 Ca 20 26 20
48
20 48 20 Ca 20 28 20

25

Competency 1.0 ( Investigates Scientific findings about the structure
of matter and quantity.

Competency level 1.3 ( Explain the Properties of compounds using it`s bonds.
Activity 1.3 ( Let us Investigates the Properties of compounds using it`s
bonds.
Time ( 120 minutes
Quality inputs ( ² Atomic models arranged according to instructions in
annex 1.3.1
² Two copies of instructions for exploration given in

annex 1.3.2
² Two work stations arranged according to instructions
given in annexe 1.3.3
² Two copies of the article "Chemical bonds" given in
annex 1.3.4

Step 1.3.1 ( ² Join the atomic models accordingly with the help of the
students.
² Lead a discussion highlighting the following points.
² Bonds are formed between atoms by the electron.
² Two electrons join to form a bond between two
atoms.
² When a chemical bond is formed ,the atoms that go to
form the bond behave the following fashion.
² One atom donates an electron from its last energy
level to the other atom.
² The election donated by one atom is accepted by the
other atom.
² The positive ion formed by the donation of the eletron
and the negative ion formed by the acceptance of
electron are attracted.
² When there is no formation of ions,electron pairs are
shared between two atoms
² During the formation of bonds the atoms try to
achieve the maximum inert gas configuration.

.
² An atom reach the maximum nobel gas configuration by
forming one or more bonds.
² Molecules are formed by atoms joining together by
chemical bonds.
² A molecules consists of two or more atoms which may be
homogeneous or heterogeneous.
² When chemical bonds form between heterogeneous atoms
compounds are formed.
² It is possible to develop the chemical equation of a com
pound by indicating the different number of atoms in a

compound molecule using the symbols of elements.
(15 mts)

Step 1.3.2 : ² Divide the class into two groups.
² Provide the groups with instruction for exploration the
article,demy papers and pastel.
² Prepare them to present their findings to the whole class.
(60 mts)

Step 1.1.3 (² Get each group to present their findings to the class.
² Get the other groups to propose constructive suggestions,
That,
² Atoms of elements by releasing electrons become positive
ions,and by receiving electrons become negative ions.
² The positive ions are named cations and the negative ions as
anions.
² There are ions which are formed from a single atom or from
a number of atoms.
² Oppositely charged ions are attracted together and thereby
forming ionic bonds,
² When ions get together to form a compound,the arrange
ment of ions in space is called the ionic lattice.

² The ionic compounds have the following inherent properties.
² Solid crystalline substances made up of ions.
² Have high melting points and boiling points.
² Soluable in polar liquids.
² Conducts electricity in the fused state as well as in solution.
² A molecule is a unit formed by the union of more than one
atom of similar or dissimilar elements.
² Atoms of some elements in the solid state are arranged in a
definite pattern in space.
² The structures which are formed by the arrangement of atoms
of elements in a definite pattern are called atomic lattice.

² Some compound molecules,in the solid state,are arranged in
a definite pattern in space.
² The structures formed by the arrangement of compound
molecules in a definite pattern in space are known as molecular
lattice.
² When bonds are formed the presence of electrons are
indicated by a dottod cross.
² A single bond between two atom is indicated by a short line
in between them.
² Depending on the number of electron pair which go to from
the bond,the bonds are known as single bond,double bond or a
triple bond.
² The electron pairs in the valency orbit that do not take part in
the formation of bonds are called lone electron pairs.
² The compounds which are formed by covalent bonds have the
following properties.
² Mostly occur as neutral molecules made up of a number
of atoms.
² Occur in Solid,liquid,and gaseous state.
² Most compounds have low melting points and boiling
points.
² Some are soluble in water.
² Do not conduct electricity in aqueous solution.
² The ability of an element to combine or its combining power is
called valency.
² The number of electrons of an atom of an element that take
part in the bonds is equal to its valency.
² Ions as well as radicals have a valency.
(45 mts.)

Criteria for Assessment and evaluation :
² Explain how ionic and covalent bonds are formed.
² Accepts the fact that there is a relationship between the chemi
cal properties of a compound and the nature of bonds.
² Investigates the physical properties of ionic and covalent
bonds.
² Use symbols as a method of presenting data.
² Make use of models to video concept.
Annexe 1.3.1
Instructons to prepare models :

Make models,as given in the diagrams,using the rigifoam sheets.

H Na Mg

Mg O O

N Cl

Annexe 1.3.2
• You are intrested with the exploration of one of the two main groups of classifications of
chemical compounds according to the nature of their bonds.
• Covalent bonds
• Ionic bonds
• Using the article on chemical bonds,discuss about the nature of the bonds with regard to
the compounds allocated to you.
• Present by using models and symbols how the bonds are formed in the type of compounds
allocated to you giving three examples.
• Calculate the relative molecular mass of the compounds making use of the relative atomic

mass.
• Find the combining power of ions,groups of ions or atoms in the compounds provided.
• Find out whether there are other compounds which could be developed from these ions,ion
groups,or atoms.
• Investegate the solubility in water,physcial nature,heating in the air and conduction of
electricity by an aqueous solution of the compounds in your work station.
• Be prepared to present your finding to the class.

Annex 1.3.3
Instructions for setting up workstations
• Work station 1
• Sodium chloride
• Calcium hydroxide
• Copper sulphate
• Work station 2
• Glucose
• Ethanol
• Urea

• Keep the following materials in both workstations.
• water
• Two drycells
• One metre of connecting wire
• Torch bulb
• Two carbon rods
• Two beakers
• Tin cover and holder
• Burning spirit lamp

Annex 1.3.4

Chemical bonds

Ionic bonds,ionic compounds and their properties.

An ion is a positively or negatively charged atom or a cluster of atoms.
Na atom Na+ ion + e
Mg atom Mg2+ion + 2e
Cl atom + e Cl- ion
S atom + 2e S2-ion

Examples for ions formed by a cluster of atoms are given below.These are known as ion
radicals.
Ammonium ion(NH4)+
Nitrate ion(NO3)-
Sulphate ion(SO4)2-
Phosphate ion(PO4)3-

In electric fields positive ions are attracted to the cathode and the negative ions to the anode.As
such if the charge in the ion is positive it is called a cation and if the charge is negative it is called
an anion. Ionic bonds is formed between positive ion formed by donating completely one or
more electron in the outer most shell of one atom to another atom,and the negative ions formed
by accepting those electrons.This is due to electro statatic attraction between the oppositely
charged ions. Consider following examples.

Ionic compounds have the following endemic properties.
• consist of ions which are oppositely charged.
• Mostly occur as crystalline solid substances.

1. The Nature of Bonding in Sodium chloride

²² ²²
× × × ²² × × ²²
× ² × ²
× × ² ²²
² ²→ × × ×² ²²
²²
× × ²² × × ²²
× ² × ²
× × ²² ×× ²²
²² ²²
Sodium Atom Chlorine Atom Sodium ion Chloride ion

(Na) (Cl) (Na+) (Cl-)

2' The Nature of Bonding in Lithium Oxide

Oxygen Atom
LithiumAtom × × Lithium Atom
• × •
× ×
Li • O • Li

• × •
× ×

Lithium ion Oxide ion
× × 2-
Lithium ion
+ × +
• •
Li × ×
• O
• Li

• × •
× ×

3' The Nature of Bonding in Magnisium Oxide
× 2-
×

→ (Mg)2+ × O
Mg × O

Magnisium Oxide ^MgO&

4' The Nature of Bonding in Calcium Chloride
_

Cl × Cl
×

→ (Ca)2+ _
Ca
×
×

Cl

Cl

Calcium Chloride ^CaCl2&

Ionic compounds have the following endermic properties.
• Consist of ions which are oppositly charged.
• Mostly occur as crystaline solide subtances.
• High melting points and boiling points.
• Most soluble in water.
• Conducts electricity in aqueous solutions and in the fused state.(heated and liquified)

Covalent bonds and properties of covalent compounds

A molecule is an electrically neutral cluster of atoms which is made up of more than one atom
which are of the same element or different elements by sharing electrons.
Here the electrons are shared in such a way that the atoms achieve the electronic configuration
of noble gases.
Each of these shared pair of electrons is a chemical bond.It is indicated by a single short line.

• + •
H
×
H → H
× H

Two Hydrogen Atoms Hydrogen molecule
Outer most shell has one electron One electron pair keep share
In order to obtain of full outer energy
level and gain the electron configuration
of the nobel gas Helium

•• ×× •• ××

• • + × • • ×
•
Cl Cl → • Cl × Cl ×
× ×
•• ×× •• ××

Two Chlorine atoms Chlorine molecule (Cl2)
Outer most shell has seven One electron pair keep share in orde to obtain
electrons of full outer energy level and gain the electron
configuration of the nobel gas Argon

×
²
² × ² ² ×
² ² + × O × → ² O × ×
O
²
×
O

²² ××
Two Oxygen atoms Oxygen Molecule (O2)
Outer most shell has six electrons.
Two electrons pair keep share.In order to
obtain of full outer energy level and gain the
electron configuration of nobel gas Neon

×
²
²
² ² + ×
×
× →
² ×
² ×
² N N ² N ×
² N ×
×
² ×
Two Nitrogen atoms Nitrogen molecule
(N2)
Outer most shell has five electrons
Three electron pain keep share. In order to
obtain of full outer energy level and gain the
electron configuration of nobel gas Neon

Similarly stucture of water molecule can be shown as follows.

×× ² H
H
²
×
×

×

× × →
×
²
×

×
×

× ² H H

Oxygen atom Two Hydrogen atoms Water molecule ^H2O&

Pay your attention to the nature of bonds of Carbon dioxide and Amonia molecules given
below.
××

×
× ×
²
× ×
× × × ×
× ²
² ² → ²
× ×
×× ² ²
×
² × ××
×
×
× Carbon atom Carbon dioxide molecule (CO2)

×
Two Oxygen atoms

² H

× ××

× ² ×
H
→ ×
× N
H ² N
² H

× × ²
Nitrogen atom ² H
H

Three Hydrogen atoms Ammonia molecule (NH3)

The number of short lines drawn between the atoms shows the number of electron pairs
shared by the atoms.If the number of shared electron pairs is one,it called a single bond,if two
a double bond and if three, a triple bond. When the bonds are indicated by short lines the
electrons in the outermost shell which do not take part in bonds should also be indicated.
•• •• •• ••
H-H • Cl Cl • O O • N N•
• •
•• •• • •• •• •

Covalent compounds have the following endemic properties.
•Mostly occur as small neutral molecules made up of few atoms.
•Occur in the solid,liquid and gaseous states.
•Most compounds have low melting points and boiling points.
•Some are soluble in water.
•Do not conduct electricity in aqueous solution.

Ionic lattice

The structure which indicates how the ions are arranged in a three dimensional space in a
chemical compound is called an ionic lattice.In the case of some elements the atoms are
arranged in a lattice.The structure of arrangement of atoms which are joined by covalence
bond is a three dimentional space is called an atomic lattice.
Eg1: Carbon-Graphite
Eg. NaCl ionic lattice

Every atom of carbon in graphite exit in a two dimensional
lattice by combining with three other carbon atom by single
bonds.Graphite blocks are formed by arranging these layers
one on top of another.The bonds between these layers are
weak and as a result one layer could slide over another easily.
Because of this graphite is used as a lubricant.

Eg2: Carbon-diamond

In Diamond every carbon atom forms four covalent bonds
with four other carbon atoms and as indicated in the diagram
in the form of a three dimensional lattice.Diamond has a high
value because it is the hardest substance in nature and is also
because it is a very rare and attractive mineral. Making use
of the fact that it is the hardest substance it is used to make
delicate parts of instruments which should not be wasted
and in glass cutting.

Molecular lattice

some elements which occur as molecules or molecules of compounds sometimes are arranged
in space as a lattice.The structure which indicates the three dimensional arrangement of
molecules in space is called amolecular lattice.

Eg. Moleculer lattice of Silicon dioxide ( SiO2)

The combining power or the combining ability of an element known its' valency. The following
table indicates the valency of some elements and ion radials.

Valency
1 2 3
Lithium Li+ Magnesium Mg2+ Aluminium Al3+
Sodium Na+ Calcium Ca2+ Iron(III) Fe3+
Metal Potassium K+ Copper(II) Cu2+
Silver Ag+ Zinc Zn2+
Copper^I& Cu+ Irona(II) Fe2+
Lead Pb2+
Barium Ba2+

Hydrogen H+ Oxide O2- Nitride N3-

Non Fluoride F- Sulphide S2-
Metal Chloride Cl-
Bromide Br-
Hydride H-

Hydroxide OH- Carbonate CO32- Phosphate PO43-
Nitrate NO3- Sulphate SO42-
Iron +
Radical Ammoinum NH4
Hydrogen HCO3-
Carbonate

The chemical formula of a compound is by using symbols and the number of different atoms in
the molecule of the compound,

H2 In the hydrogen molecule there are two hydrogen atoms.
Cl2 In the chlorine molecule there are two chlorine atoms
NH3 In the Ammonia molecule, there is one Nitrogen atom and three hydrogen atoms.
H2SO4 In Sulphuric acid molecule, two atoms of hydrogen, one atom of sulpher and four
atoms of Oxigen

When a compound if formed by atoms of two elements they must be constructed in such a
way so as to balance the valencies of atom

Example- 1. Sodium chioride is made of univalent Na+ ion and univalent Cl- ion
combining .Formula - NaCl
2. Magnesium chloride is made by bivalent Mg2+ ion and two
univalent Cl- ions.-Formula- MgCl2
3. Magnesium oxide is made up of bivalent Mg2+ ion and bi valent
oxygen O2- ion combining formula -MgO
4. Sodium hydroxide is formed by univalent Na+ combining with uni
valent(OH)- ion.Formula-NaOH
5. Sodium carbonate is formed by two ions of univalent Na+ and
bivalent (CO3)2- . Formula Na2CO3
6. Copper sulphate is formed by bivalent Cu2+ combining with
bivalent (SO4)2- ion, Formula CuSO4
7. Aluminium sulphate is formed by two atoms of trivalent Al3+ ion

combining with three ions of bivalent (SO42-)ions
. Formula Al2(SO4)3
8. Water molecule is formed by two atoms of univalent hydrogen
combining with one atom of bivalent oxygen. Formula H2O
9. To develop the above formulae the valency of atoms,ions or ion
radicals of simple compounds could be made use of,seewhether it
is possible to draw a connection between the formula of the
compound and the valency of atom or ion radicals using the
above example.

Competency 1.0( Investigates the Scientific findings about the
structure of matter and quantity.

Competency level 1.4 Use mole to quantify elements and Compounds.
Activity 1.4 ( Let us quantify matter.
Time ( 120 minutes
Quality inputs ( ² An enlarged copy of data table given in annexe 1.4.1
² Two copies of instructions for exploration given in
annexe 1.4.2

Step 1.4.1 ( ² Asks from the students that if the mass of a two rupee coin is
8g what is the easiest way to seperate ten thousand of those
coins.
² Exhibit the data table to the class.
² Direct students to get together in group of two and calcu
late the number of atoms in a relative mass of an atom,in
grammes,or the number of molecule in grammes.
² Lead a discussion highlighting the following facts.
² The number of atoms in a relative atomic mass of an
element in grammes has been calculated to be about
6.022x1023
² The number of molecules in a relative molecular mass
of a compound in grammes has to be calculated to be
about 6.022x1023
² The number of atoms in a relative atomic mass of an
element in grammes or the number of the molecules
in a relative molecular mass of a compound in grammes
is 6.022x1023
² A mole of a substance is 6.022x1023 fundamental enti
ties of that substance
6.022x1023ffundamental units which make up matter,the
atom,molecule,ion,subatomic particles is called a mole
of that matter.
² Mole is an international unit which measure the quantity
of matters.

² The number of fundamental units included in a mole is
constant,this constant called the Avogardo Constant(L
or NA)
( ² Avogadro constant is NA= 6.022 x 1023 mol-1
² The mass of a mole of substance is called the molecu
lar mass of that substance.(M)
Eg.In a mole of carbon atom mass of 6.022x1023
carbon atom is 12g
Hence molecular mass of carbon is 12gmol-1
Eg.In a mole of water there are 6.022x1023 molecules
of water.Its` mass is 18g.Hence the molecular mass
of water is 18gmol-1

² The value of the mass of an element when stated in
grammes is equal to the relative atomic mass of that
element.
² The value of the mass of a mole of compound when
stated in grammes is the relative molecular mass of that
compound.
² When it is required to weight substance of small mass
like atoms,molecules ,it is easy to weight the required
amount of that substance.
² When we want to seperate a quantity of substance,the
knowledge of the molecular mass of that substance is
useful.
(15 minutes)
² Provide each group with copies of the article instruc
tions for exploration,demy paper and marker pens.
² Assign tasks and engage groups in exploration.
(60 minutes)
Step 1.4.3 ² Get groups to present their findings to the class.
² Give the first opportunity to the respective group to elaborate on the

presentation.
² Get the other groups to propose Constructive suggestions.
² Summerize highlighting the following points.
² If the mass of an element/compound(m),and the number of
moles of Atoms/molecules(n)
The relationship is n=m/M
² The mass of a quantity of moles(n)of an element /compound
is(m),we get the following relationship.
m = Mxn
² The mass of an (N) number of atoms of an element is(m),
The relationship we get is
m = MxN/NA
² The relationship we get when a mass(m) of an element/com
pound contain(N) number of molecules is
N = (m/M)xNA
² When (n) number of moles of an element/compound contain(N)
number molecules the relationship is
N = nxNA
² The relationship of mass of an atom /molecule(m0) is shown by
m 0= M/NA.
² When it is required to get a specific quantity of matter and
quantitative calculations in chemistry,the above relation
ships are useful.

(45 mts)

² Define the terms mole,Avogadro constant and molecular mass.
² Accepts that in chemistry when there is a need to quantify elements/compounds.
² Develop relationsship associated with quantitative of elements and compounds.
² Shows relationalships using equation.
² Investigates the accuracy of a relationaship.

Annex 1.4.1
Data Table

Element Mass of Relative Compound Mass of Relative
a atom/g Atomic a compound Molecular
Mass molecule/g Mass

H 1.66 x 10 -24 1 H2O 2.99 x 10 -23 18

CH4 2.65 x 10 -23 16
C 1.99 x 10 -23 12

NH3 2.82 x 10 -23 17
N 2.32 x 10 -23 14

CO 2 7.31 x 10 -23 44
O 2.66 x 10 -23 16

Annex 1.4.2

² Focus your attention to the type of matter given below assigned to your group.
² Element
² Compound
² Develop suitable expressions to quantify the matter assigned to you.It is possible to include
Avogardo constant NA whereever suitable.
² m0 mass of an electron of element/ mass of a molecule of a compound whose
molecular mass is M
² mass m of an element/compound contains n moles of atoms/molecules whose
molecular mass is M
² mass m of an element/compound contains N number of atoms/molecules
whose molecular mass is M
² In n moles of an element/ compound contained N atoms/ molecules whose
molecular mass is M
² By making use of the relationships appropriately, select the problems and final solutions to
the matter assigned to you.
² The molecular mass of carbon is 12gmol-1 .Find the number of moles in 10g of carbon.
² The releative atomic mass of oxygen is 16.Find the number of atoms in 10g of oxygen.

² The molecular mass of nitrogen is 14gmol-1.Find the mass of an atom of nitrogen.
² The molecular mass of hydrogen is 1g mol-1. Find the number of hydrogen atoms in 0.1
mol of hydrogen.
² The molecular mass of carbondioxide is 44gmol-1.Find the number of atoms in 20g of
carbon dioxide.
² The relative molecular of Methane is 16gmol-1.Find the number of moles in 0.2g of
methane.
² The molecular mass of water is 18g mol-1.Find the number of moles in 20g of water.

Competency 2.0 ( Investigates Periodic patterns in properties of
elements.

Competency level 2.1 ( Investigates properties of elements change according
to the atomic number.
Activity 2.1 ( Let us investigate the changing patterns in properties of
matter..
Time ( 120 minutes
Quality inputs ( ² Four copies of instructions for exploration given in annex
2.1.1
² Four copies of "Physical properties of matter" table given

in annex 2.1.2
² Graph papers demy papers and pastel
Teaching learning process (
Step 2.1.1 ( ² Display the class an enlarged figure of the diagram
below.

)

² Get some of the student to complete the pattern given
above.
² Conduct a discussion highlighting the following points•
² There is a pattern in the change in direction of the
arrow.
² After a definite number of squares we come across an
arrow which is directed in a similar direction.
² Patterns which occur again and agian at definite
intervals are known as periodic pattern
. ² Awareness of patterns simplify science education.
(15 mts)
I
² Provide the groups with exploration
instructions,table,graph papers,demy papers and pastel.

(60 minutes)
45

tions,
That,
² C and Si elements are at the top graph on of melting
points
² He,Ne,Ar elements are at the bottom of the graph on
melting points.
² According to the graph the variation in temperature of
liquifactors shows a periodic pattern.

² Element C and Si are at the top of the graph boiling
points.
² Elements He,Ne,Ar are at the bottom of the graph
giving boiling points
² According to the graph the variation in boiling points
shows a periodic pattern.
² Elements B and Al are at the top of the graph
givining density
. ² Elements H,N,Na and K are at the bottom of the
graph giving density.
² According to the graph indicating variation in density
shows a periodic pattern.
² The volume occupied by a molecular mass of an
element when expressed in cubic centimetres it is
called the atomic volume.
² In the graph giving the atomic volumes of
elements,He,Na, and K elements are placed at the
top.
² In the graph giving the atomic volumes of elements B
and Al elements are placed at the bottom.
² According to the graph, variation in atomic volumes
of elements shows a periodic pattern.
² Properties of elements is a periodic function of the
atomic number.

(45 mts)

46

² Explain the variation in pattern of temperature of liquifaction/boiling point/density/
atomic volume, of elements against the atomic number.
² Appreciates that there is a periodic variation shown by the atomic number against
properties of elements.
² Draw graphs to show variation of properties of elements.
² Explatins a graph.
² Makes educational activities easy by understanding patterns.

Annex 2.1.1

² Your group is expected to investigate how one of the properties given below vary according
to the Atomic number.
² Melting point of elements
² Boiling points of elements
² Density of elements
² Atomic volume of elements
² Using the table given draw a graph with Atomic number against the respective property.
² Enlarge the graph developed by you, and draw on a demy paper.
² Be prepared to present your findings to the whole class

47

Annex 2.1.2

Physical Properties of Elements

Density Atomic
Elements Atomic Melting Boiling
at 20 0C volume
number point/ 0C point/0C
g cm-3 cm3 mol-1

H 1 -259 -253 0.071 14.1

He 2 -270 -268.9 0.125 31.8

Li 3 180 1330 0.53 13.1

Be 4 1283 3000 11.84 4.9

B 5 2030 2550 2.34 4.3

C 6 3600 4800 2.25 5.4

N 7 -210 -196 0.81 17.3

O 8 -218 -183 1.14 14.0

F 9 -220 -188 1.15 17.1

Ne 10 -249 -245 1.20 16.8

Na 11 97.8 890 0.97 23.7

Mg 12 651 1100 1.74 14.0

Al 13 660 2500 2.70 10.0

Si 14 1410 2400 2.42 16.6

P 15 44 280 2.34 14.1

S 16 113 445 2.07 15.5

Cl 17 -103 -35 2.00 18.7

Ar 18 -189 -186 1.66 24.0

K 19 63 766 0.87 45.0

Ca 20 840 1500 1.55 26.0

(Source : Book of Data for Teachers of Chemistry / 1989, NIE)

48

Competency 2.0 ( Investigates Periodic patterns in properties of
elements.

Competency level (
2.2( Investigates the realtionship between the position in
periodic table and the properties of elements.

Activity 2.2 ( Let us return to the periodic table.

Time ( 120 minutes
Quality inputs ( ² Provide a large elaborate periodic table in annexe 2.2.1
² Four copies of Instructions for exploration given in

annexe 2.2.2
² Four copies of "Diversity in Physical and chemical
properties" of elements in annexe 2.2.3
² Graph papers demy papers and pastel
Step 2.2.1 ( ² Exhibit the periodic table to the class.
² Direct the students to observe the data indicated by
symbols,numbers and colours.
² Conduct a discussion highlighting the following point.
²The elements are grouped in the periodic table for
easy study of element.
²The transverse rows of the periodic table are called
periods,they numbered as 1,2,3,4 etc.The vertical
rows are called groups and they are numbered
I,II,III,IV,V,VI,VII,VIII or O
²The elements are grouped in the periodic table as
periods and groups ,according to a foundation based
on argument.
(15 mts)

² Provide the groups with instructions for exploration
graph papers,demy papers and pastel.

(60 minutes)

49

tions,
That,
² The number of electrons in the outermost shell of an
atom of the element is equal to the number of the
group to which the element belongs.
² The number of shells containing electrons is equal to
the number of the period to which the element
belongs.
² Most elements to the left hand side of the periodic
table are found in the solid state.
² The elements at the top on the right hand side of the
periodic table are in the gaseous state.
² The elements in the left hand side of the periodic table
are mostly metals and when you go forward along a
period non metals are found.
² When you move down along a group containing
metals there are elements which show strong metallic
properties.
² The density of elements from groups I to IV in 2 and
3 periods,increase regularly ,but from V to O it
decrease regularly.
² When we move forward along 2 and 3 periods,the
atomic volume decrease up to group III,gradually
increase thereafter.
² When we move forward along 2 and 3 periods,from
group I to IV the melting point and the boiling point
increase where as groups V,VI,VII and O the
elements have very low melting point and boiling
points.
² When we move forward along a period,the
oxides,chlorids and hydrides changes from ionic
to covalent types.
(45 mts)

50


² Explain varying patterns of properties of elements when moving forwards along periods
and down along groups.
² Appreciate that the elements are classified in the periodic table for easy study of properties
of elements.
² Discovers connection between the position of element in the periodic table and the proper
ties of the element.
² Understands natural patterns.
² Use graphs to present data meaningfully when it is suitable.

51


.

52
Periodic Table
Annex 2.2.1

Annexe2.2.2
² Your group is assigned to study the relationship between the place in the periodic table and
its properties in one of the following.
² moving forward along the second period
² moving forward along the third period
² moving down along groups I,II,III,IV
² moving down along groups V,VI,VII,O
² By using the periodic table and the table privided understand the patterns in the following.
² Number of electrons in the outer most shell
² Metallic,non metallic,physical state

² Density
² Atomic volume
² Melting point/Boiling point
² Acidicity-Basicity of oxides/Hydrides
²Be prepared to present your findings to the class using graphs whenever required.

53

Annex 2.2.3

Diversity of Chemical and Physical Properties of elements

Atomic
Electronic Metalic/ Nature of Density Volume melting Boiling
Elements Atomic Non
Number Config. Oxide cm-3 point 0C point0C
Metalic gcm-3
mol
H 1 1 0.071 14.1 -259 -253
He 2 2 0.125 31.8 -270 -268.9
Li 3 2, 1 0.53 13.1 180 1330

Be 4 2, 2 11.84 4.9 1283 3000
B 5 2, 3 2.34 4.3 2030 2550
C 6 2, 4 2.25 5.4 3600 4800
N 7 2, 5 0.81 17.3 -210 -196
O 8 2, 6 1.14 14.0 -218 -183
F 9 2, 7 1.15 17.1 -220 -188
Ne 10 2, 8 1.20 16.8 -249 -245
Na 11 2, 8, 1 0.97 23.7 97.8 890
Mg 12 2, 8, 2 1.74 14.0 651 1100
Al 13 2, 8, 3 2.70 10.0 660 2500
Si 14 2, 8, 4 2.42 16.6 1410 2400
P 15 2, 8, 5 2.34 14.1 44 280
S 16 2, 8, 6 2.07 15.5 113 445
Cl 17 2, 8, 7 2.00 18.7 -103 -35
Ar 18 2, 8, 8 1.66 24.0 -189 -186
K 19 2, 8, 8, 1 0.87 45.0 63 766
Ca 20 2, 8, 8, 2 1.55 26.0 840 1500

Ga 31 2, 8, 18, 3 5.90 11.8 30 2237
Ge 32 2, 8, 18, 4 5.46 13.3 937 2837
As 33 2, 8, 18, 5 5.72 13.1 613 sublimation
Se 34 2, 8, 18, 6 4.80 16.5 220 685
Br 35 2, 8, 18, 7 3.12 25.6 -7.2 58.5
Kr 36 2, 8, 18, 8 3.00 32.3 -157 -153

54

Competency 3.0 ( Use chemical reactions appropriatily to fulfil
requirments in life.
Competency level 3.1 Classify chemical recations

Activity 3.1 ( Let us understand about types of reactions.
.

Time ( 120 minutes
Quality inputs ( ² !0 cm3 of concentrated nitric acid
² A copper wire of 30 cm length,half of which is made into
a coil

² Boiling tube
² Four work station prepared according to instructions
given in annex 3.1.1
² Four copies of instructions for group exploration given in
annexe 3.1.2
² Demy paper and pastel

Step 3.1.1 . (
² Introduce the coiled end of the copper wire into the
boiling tube containing concentrated HNO3and display to
the class.

² Direct the students to observe what happens
² Conduct a discussion highlighting the following points.
² When conc HNO3 reacts with Cu metal given
coloured Cu(NO3)2 solution is formed and reddish
brown coloured NO2is given out.

55

² During chemical reactions ,simple substances are
converted to complex substances or complex
substances are converted to simple substances.
² The chemical reactions could be grouped according
to the nature of the reaction.

(15 mts.)

Step 3.1.2 ( ² Divide the class into four groups.
² Provide the groups with instructions for exploration
graph papers,demy papers and pastel.

(60 minutes)
tions,
That,
² Elements Iron and sulphur combine to form sulphide.
² Magnesium and oxygen combine to form magnesium
oxide.
² When a different compound is formed when an ele
ment-element,or element-compound or compound-
compound combine is known as a combination
reaction.
² When potassium permanganate is heated it dissociates
into simple compounds.
² When hydrogen peroxide is heated it dissociates into
simple compounds.
² When a compound dissociates into simple compounds
or to elements and simple compounds,it is called a
dissociation reaction.
² Metal magnesium,reacts with copper sulphate releasing
Cu metal forming Magnesium sulphate.
² Zinc metal reacts with dilute sulphuric acid liberating H2
gas and form zinc sulphate.

56

² When an element displace another element in a compound
and takes its place and form another compound it is
called single replacement reaction.
² When calcium chloride react with sodium carbonate
calcium carbonate and sodium chloride is formed.
² When ferrous sulphate reacts with sodium hydroxide
,ferrous hydroxide and sodium sulphate is formed.
² When an element or a radical of a compound,reacts with
an element or a radical of another compound undergo an
exchange reaction it is known as a doubel replacement
reaction.

(60 mts)
² Classify chemical reaction and describe using examples.
² Apperciates that chemical changes during a reaction can be made use of to classify chemical
change.
² Demonstrate chemical reaction.
² Data given using symbols are made use of gainfully.
² Demonstrate skills in using equipment.

Annexe3.1.1
Instructions to set up work stations
Set up four work stations by keeping the following materials.label materials and equipments.
Work station 01
² Iron filings 3.5 g
² Sulphur powder 1.5g
² Boiling tubes 01
² Holders 01
² Sprit lamp 01
² Piece of Magnesium ribbon 01
Work station 02
² KMnO4 4g
² H2O2 solution 20 cm3
² Boiling tubes 02
² Holders 01
² Spirit lamp 01
² Dry ekle pieces 02

57

Work station 03
² 2 cm length of clean magnesium ribbon
² Solution of Cuso4(2g of Cuso4 in 100cm3 of water)
² Zinc pieces 1g
² Dilute H2SO4 acid 10 cm3
² Two test tubes
² Test tube rack
Work station 04
² CaCl2 solution (CaCl2 0.5g in 10 cm3 of water)
² Na2CO3 solution (Na2CO3 0.5g in 10 cm3 of water)
² FeSO4 solution(FeSO4 0.5g in 10 cm3 of water)

² NaOH solution (NaOH 0.5g in 10 cm3 of water)
² Four test tubes
² Test tube rack


² Concentrate your attention on the two reactions assigned to your group.
² Heating iron filings with sulphur/burn magnesium in air
² Heating of Potassium permanganate/Heating of Hydrogen peroxide
² Reaction between magnesium and Copper sulphate/Reaction between zinc and dilute
sulphuric acid
² Reaction between Calcium Chloride and Sodium Carbonate/Reaction between
ferrous sulphate and Sodium hydroxide
² Familiarize yourself with the materials kept at the respective work station.
² Conduct the reaction and record your observations.
² Write down the equations for the chemical reactions.
² Using prefered symbols,develop a common equation to represent both reactions.

58

Competency 3.0 :Use chemical reactions appropriatily to fulfil
requirments in life.
Competency level 3.2 : Investigates interaction between matter and electricity

Activity 3.2 : Let us find out connection betwen matter and electricity
.
Time : 120 minutes
Quality inputs : • copper and zink sheet of 2 cm x 5 cm size.
• Fruit (Lime,Orange,Apple) or potatoe yam
• LED bulb
• Three copies of instructions group exploration given in

annex 3.2.1
• Common table prepaired according to instructions in
annex 3.2.2
• Demy paper and pastel

Teaching learning process : • Insert the zink and copper sheets into the fruit
(Lime,Orenge,Apple) or potato yam, so that they are
close together but not touching. Connect the LED bulb
amd demostrate its' glow.
• Conduct a discussion highlighting the following.

• That electricity is produced when subtances in the
fruit/potato yam interacts with the metals.
• There is an inter connection between matter and
electricity
(15 mts.)
Step 3.2.1 • Divide the class into three groups.
• Provide the groups with instructions for exploration,
demy paper and pastels.
• assign the tasks and engage the groups in exploration.
• Prepare them to present their findings to the whole class
(60 mts.)

Step 3.2.2 : • Get the group to present their findings to the class.
• Give the first opportunity for elaboration to the respec
tive group which made the presentation.
• Get the other groups to propose constructive suggestions

59

• Elaborate highlighting the following points.

• The following observations were noted when Copper
(II) Chloride solution was electrolyse.
• Copper was deposited on the electrode connected to
the negative terminal of the battery.
Cu2+ (aq) + 2e Cu(s)
• Chlorine gas was liberated at the electrode connected to the
positive terminal of the battery.
2Cl - (aq) + 2e Cl2 (g) + 2e
• When a moist litmus paper was exposed to Chlorine gas it
decolourised.
• The green colour of the solution grsduslly redused.
• temperature of the system increased.

( 45 mts)
)

• With lighting of the bulb, flow of current through the electrolyte
was confirmed.
• It is possible to change matter by supplying electricity from
outside.
• Effecting a chemical change at the electrodes by passing a
current through an ionic solution (electrolyte) is known as
electrolysis.
• During electroplating of the iron plate the following observa
tions were made.
• Copper was deposited as a thin film on the iron plate.
Cu2+ (aq) + 2e Cu(s)
• Copper plate gradually dissolved.
Cu(s) Cu2+ (aq) + 2e
• Colour of the solution did not change
• Level of the solution increased.
• The depositing of a metal on a surface is known as Electroplat-
ing.
• By electroplating a surface gets a metallic finish and protection.
• When bulb is connected between Copper and Zink plates
immersed in dilute sulphuric acid,
• The bulb ignited.
• Zink plate gradually dissolved.
• Gas bubbles got collected on the Copper plate.
• When bulb is connected between Copper and Zink plates
immersed in dilute sulphuric acid, an electric current is pro-
duced
• A set up where an electric current is produced, associated with
a chemical change is known as an electric cell.
• Electric currrent could be obtained from dry cells and batteries.
60

• Removal of electrons from an atom, an ion or a radical is
Oxcidation.
• Intake of electron from an atom, an ion or a radical is Reduction.
• Electrode where Oxidation is taking place is known as Anode.
• Electrode where reduction is taken place is known as Cathode.
(45 mts)
Criteria for assesment and evaluation

• Explain about electric cells, electrolysis and electroplating.
• Appreciates that it is possible to enhance daily living using the
relationship between matter and electricity.

• Investigates the relationship between matter and electricity.
• Prepair a diagram with a set up selecting the materials.
• Use demostration effectively for communication.

Instruction for group exploration

• Your group is assigned to study the interaction between matter and electricity using one of
the following.
• Chemical cells.
• Electrolysis
• Electroplating

• Study the diagram in the respective precincts , select the necessary materials to prepare the
set up from the commen table.
• Make the setup.
• .Observe the following and report on the set up relevant to you
• Changes that take place at the electrodes.
• Changes in the solution.
• Is there a change in temperature during the reaction?
• Did the bulb ignit?
• What are the possible ions in the solution provide to you?
• Be prepared to present your findings to the class along with a
demostration.

61

Annex 3.2.2
Keeping diagrams in the work stations

Work Station 1 4V _
+

Bulb
+ _

Carbon Electrodes

CuCl2 Aqeous Solution

Eletrolysis
Work Station 2
4V _
+

Bulb
+ _
Cu Electrode
Fe Electrode

CuSO4Aqeous Solution

Electroplateing
Work Station 3 Bulb

Zn Electrode
Cu Electrode

Dil. H2SO4 Solution

Chemical Cell

62

Annex 3.2.3

Materials and apperatus on common table

• Carbon Electrodes 02
• Copper electrodes 02
• Zinc electrodes 01
• 2 cm x 5 cm Iron plate (surface cleaned )
• Dry Cells 06
• 1.5 V Bulbs 03
• Thermometers 03
• 100 cm3 Beaker 03
• 0.5 mol dm-3 CuCl2 aqeous solution 100 cm3

• 0.1 mol dm-3 Dil. H2SO4 Solution 100 cm3
-3
• 0.1 mol dm CuSO4 Solution 100 cm3
• Litmus papers
• Connecting wires

α

α

±±

.

63

Competency 3.0 ( Use chemical changes suitably to fulfil necessities
in life

Competency level 3.3 ( Investigates reaction patterns of pure metals.

Activity 3.3 ( Let us explore the reactivity of metals.

Time ( 120 minutes
Quality inputs ( ² Piece of Sodium metal,knife and a basin of water
² Four work stations prepared according to instrutions

² Four copies of instructions for group exploration given in
annex 3.3.2
² Demy papers and pastel
Step 3.3.1 ( ² Direct the students to observe how a cut surface a
freshly cut piece of sodium change with time.
² Demonstrate to the class the reaction between sodium
and water by putting a piece of sodium into a basin of
water.
² Conduct a discussion highlighting the following points.
² Sodium is a pure metal.
² When a freshly cut surface of sodium metal is
exposed to air for a short time it looses its shine.
² Sodium metal reacted vigorously with cold water.
² It is possible for the reactivity metals could differ
from metal to metal.
(15 mts)

Step 3.3.2 ( ² Divide the class into four groups.
² Provide the groups with exploration
instructions,table,demy papers and pastel.
(60 mts)

tions,
² When Mg,Al,Zn,Fe and Cu metals are kept in the air
for a short time there is no observable change.
² When Mg is heated it burns with a glowing flame.
² When Al, Zn, Fe and Cu are heated in air they loose
their shine.
² When Mg, Al,Zn,Fe, and Cu are heated in air it re
acts with the oxygen in the air and forms the oxide of
he metal.
Eg: 2Mg(s)+O2(g) → 2MgO(s)

² Mg metals reacts very slowly with cold water releas
ing gas bubbles.
² Al,Zn,Fe and Cu do not show any observable
reaction with cold water ,in a short time.
² Mg reacts some what vigorously with hot water
releasing gas bubbles.
² Al and Zn reacts very slowly with hot water releasing
gas bubbles.
² Fe and Cu does not show any visible reaction with
hot water,in a short time.
² When Mg,Al and Zn reacts with water,hydrogen gas
is released forming the hydroxide of the metal.
Eg Mg(s)+2H2O(l) → Mg(OH)2(aq)+H2(g)
² Mg,Al,Zn and Fe reacts with dilute acids releasing
gas bubbles.
Eg Mg(s)+2HCl(aq) → MgCl2(aq)+H2(g)
² Cu does not react with dilute acids.
² Due high reactivity of Na ,it is dangerous to heat the
metal in air or react it with acids/Hot water.
² A metal whose reactivity is high could displace a
metal whose reactivity is less from an aqueous
solution of it.
Eg: Fe(s)+Cu2+(aq) → Fe2+(aq)+Cu(s)
² It is possible to arrange the metals in their order of
reactivity in a series.
Cu<Fe<Zn<Al<Mg<Na
² The metal series arranged acorrding to decreas
ing reacrivity, is known as the activity series
² Scientists have develope the activiry series , by
including metals explore and in addition the other
metals as follows

.

² The metal series arranged according to decreasing
reactivity,is known as the activity series.
² Scientists have developed the activity series, by
including metals explored and in addition the other
metals as follows.

K

Na

Ca

Na Mg

Mg Al

Zn
Al

Zn Fe
Sn
Fe

Cu Pb

Au Cu

Hg
Exploring
metal Ag

Pt

Au

Introduced
Build up
activity metal
series

² Activity series is useful when studying about metals.


² Explanes how the activity of two metals could be compaired
² Accepts that sequential arrangement of metals in the series developed, and the activity series
in agrement.
² Compair the activity of two matals experimentaly.
² Come to conclutions basing observations
² Able to observe the effect of a factor by controlling the
variables.
Annex 3.3.1
Instructions for setting up of work stations

² Set up four work stations for activities.
² Provide the four work stations with the following materials.
² Boiling tube
² Two test tubes
² Test tube stand
² Test tube holder
² Bunsen burner
² Pieces of sandpaper
² Small Scissor
² Cold water and hot water
² Two test tube containing 10 cm3 of CuSO4 solution
² Provide the work stations with one of the following
² Six pieces each of Mg and Al
² Six pieces each of Al and Zn
² Six pieces each of Zn and Fe
² Six pieces each of Fe and Cu
(Each of these metals must be of the same size as a 2 cm length of Mg)


² For exploration you are provided with one of the following metal groups.
² Mg-Al
² Al-Zn
² Zn-Fe
² Fe-Cu
² Observe the reactivity of the metals seperately with the follwing
(cut the metal into small pieces when required)
² Air

² Cold water
² Hot water
²Dilute Hydrochloric acid
²CuSO4 Solution
² From your observations compare the reactivity of the two metals.
² Develop with a discussion a series in the ascending order of reactivity of the two metals
provided,along with sodium and gold.

Competency 3.0 ( Use chemical changes suitably to fulfil necessities
in life

Competency level 3.4 ( Use suitable methods for extraction of metals
Activity 3.4 ( Let us find about methods for extraction of metals.

Time ( 120 minutes
Quality inputs ( ² Piece of Lead,Lead monoxide,blow pipe,charcoal block
and bunsen burner.
² Two copies of instructions for group exploration given in
annex 3.4.1

² Two copies of article on "extraction of metals" in annex
3.4.2
² Demy papers and pastel
Step 3.4.1 ( ² Show the class a piece and lead monoxide
² Ask from the student about the possibility of turning
lead oxide to lead.
² Put some lead monoxide into a hole in the piece of
charcoal block,and direct the bunsen flame to the hole by
blowing through the blow pipe.
² Allow students to observe the change.
² Lead a discussion high lighting the follwing points.
² Lead is formed by the dissociation of lead monoxide
by heat.
² During extraction of some metals thermal methods
are used.
² Other methods too are used for extraction of metals
² When selecting a suitable method for extraction it is
important to consider the form in which it is available
in nature and the chemical activity of the metal
(15 mts).

69

Step 3.4.2 ( ² Divide the class into two groups.
² Provide the groups with the article on instructions for
exploration ,demy papers and pastel

(60 mts)
tions,

² Summrize highlighting the following points.

² The following points are agreeable for metals at the
top of the activity series.
² Reaction is very high
² Because they react fast with air and water they are
kept either immersed in paraffin oil or imeared with a
protective covering.
² They are available in nature as chloride of the metal.
² The metal is extracted mainly electrolysing the fused
metal chloride.
² The following points are valid for metals at the middle
of the activity series.
² Shows medium range of reactivity.
² Mainly available in nature ,as oxide of the metal
² Carbonate of the metal or Sulphide of the metal.
² Metal is extracted by thermal dissociation of
oxides,Sulphides or Carbonates.
² The following points are valid for metals at the bottom
of the activity series.
² Reactivity is very low.
² Available in nature as pure metals,not as com
pounds.
² Extraction is by separating the metal from the soil
particles by physical means.
(45 mts)

70

Annex 3.4.1

Criteria for assessment and evâlution

² Explain the basic methods of extraction of metals.
² Appreciates that there is a connection between the reactivity of the metal,from in which it is
available in nature ,and method of extraction
² Correlate the place occupied by a certain metal in the activity series and its properties.
² Gather facts by using reacting materials.
² Present the facts collected in a way understood by the others.

Annex 3.4.1

Instructions for Group exploration
² You are expected to make a study of a metal group belonging to the activity series given

below.
K
Na
² Metals with high reactivity Ca
Mg
Al

Zn
Fe
² Metals with middle rate Sn
of reactivity Pb
Cu

Hg
² Metals with low reactivity Ag
Pt
Au

² Using the artical supplied to you,gather data according to the headings given below,about the
metal group assigned to you
² Availability in nature
² Method of extraction
² How it is stored
² Gather data about the metal gold under the headings given above,and compare with metals
assigned to you.

71

Annex 3.4.2
Metal extraction

Ores in which the metal with present as the metal chloride

Main constituents The metal extracted
Ore
in the Ore

Sodium Chloride NaCl Sodium

Potassium Chloride KCl Potassium

Magnesium Chloride MgCl2 Magnisium

Calcium Chloride CaCl2 Calcium

Ores in which the metal is present metal oxide

Much constituents
Types of Ore The metal extractor
in the Ore
Haematite Fe2O3 Iron
Magnatite Fe3O4 Iron
Limonite Fe2O.2H2O Iron
Boxite Al2O3.2H2O Aluminium
Cuprite Cu2O3 Copper
Tinstons SnO2 Tin

Ores in which the metalis present as the metal carbonate

Main constitutent
Types of Ore The metal extractor
in the Ore

Callamine ZnCO3 Zinc
Limestone CaCO3 Calcium
Malkite CuCO3.Cu(OH)2 Copper
Aturaite 2CuCO3.Cu(OH)2 Copper
Magnasite MgCO3 Magnisium

72

Ores in which the metal is present as metal sulphide

Types of Ore Main constituents Metal extractor
in the Ore

Copper Pyrites CuFeS2 Copper
Zincblent ZnS Zinc
Galena PbS Lead
Zinabar HgS Mercury

Methods of Extraction
Electrolysis of Fused compound

The compound that is electrolysed to extract the metal and
Metal
the chemical reaction that take place

Available in nature as Sodium Chloride. In the Downs process
Sodium Chloride id fused and electrolysed. For it to liquify easily it is
mixed with Calcium Chloride.

→
NaCl → Na+ + Cl-
→
Sodium CaCl2 → Ca2+ + 2Cl-
² At the anode Cl2 if formed.
² At the cathode Na metal is formed.
(the diagrames mention under Sodium extraction)

Available in nature as KCl. The metal is obtained by
Potassium electrolysing the fused Chloride.

Available as CaCO3 in nature. By adding Hydrochloric acid to
this, CaCl2 is formed. Fused CaCl2 is electrolysed in Graphaite
crucible.
Calcium ² Metallic Calcium is deposited on the cathode.
² Chlorine is evolved at the Anode.

73

The compound that is electrolysed to extracts the metal
Metal
and chemical reactions take place

Magnesium Chloride is present in nature as Carnalite in sold deposites;
Magnesium Fused Carnalite is electrolysed in Iron vessels. Here mostly MgCl2
undergo electrolysis.

Aluminiumis present naturally as Boxite. (Al2O3.2H2O) This is purified
Aluminium and fused , then it is desolve in purified and fused Cryolite (3NaF.AlF3)
It is electrolysed.

2. Reduction of the Ore with Carbon or Carbon Monoxide

Metal Reactions and the way reduction is performed

Th Ore Hematite (Fe2O3) is roasted , and the oxide is obtained without
any vapourising material, These oxide is heated in a blast furnance
Iron reduced by Carbon monoxide.

Fe2O3 + 3CO → 2Fe + 3CO2
(The diagram is mention under Iron extraction)
Zinc blend (ZnS) or Calomine (ZnCO3) is roasted in air
convert to the oxide
Zinc
2ZnS + 3O2 → 2ZnO + 2 SO2 this oxide is mixed
with Coke powder and reduced.
ZnO + C Zn + CO

The Tinstone (SnO2) Ore is roasted in air and later toasted with
Tin Carbon.

SnO2 + 2C Sn + 2CO

Galena (PbS) first converted to Leadoxide.

2PbS + 3O2 2PbO + 2SO2
Lead Later , Lead is obtained as in the reaction given below.
PbO + C Pb + CO
PbO + CO Pb + CO2

74

Extraction of Sodium

Sodium is extrcted by Electrolysing fused Sodium chloride. To reduced the melting point of
Sodium Chloride to 600 0C, it is mixed with CaCl2. The fused solution is electrolysed by using
the Down's cell.

Chlorine gas

Fused Sodium metal Fused Sodium metal

Cylindrical steel
cathode

Steel diaphragm to
Fused Sodium Chlo- avoide the reaction of
ride and Calcium Sodium and Chlorine.
Chloride mixture. Carbon (Graphite)
anode

Down's cell
The cathode is made of steel and the anode is of Graphite. During electrolysis the following
reactions take place at the electrodes.

At cathode
Na+ + e Na

At anode 2Cl- Cl2 + 2e

75

Iron Extraction

The Ore that is frequently used is hematite which contains Iron (111)
Moisture,Sulphur.Arsenic are present in the ore as impurities.To remove these the ore is
roasted in air.Hematite is then mixed coke. Coke is a type of coal which produced more heat.
For this the Ore is mixed with Limestone. The heat required is supplied by coke. Limestones
remove sand in the Iron. This reaction taken place in a blast furnace.

Iron Ore,
Coke and

Limestones
gas impurities gas impurities

Hot air in Hot air in

Liquid Iron out

Blast Furnace
The diagram given above show a blast furnace. The mixture is introduced to the furnace at the
top. The temperature in this furnace is more than 1500 0C. The chemical reaction taking place
could be shown step by step as shown below.

1. The Oxygen in the air that enter the furnace with coke react to form Carbon dioxide.
C + O2 CO2
2. This CO2 reacts further with Coke and forms CO gas.
CO2 + C 2 CO
3. The CO gas reacts with Iron (III) Oxide and form Iron.
Fe2O3 + 3CO 2Fe + 3CO2
4. In addition to CO Carbon too reacts with Iron Oxide to form Iron.
Fe2O3 + 3C 2Fe + 3CO
76

Extraction of Gold

Metals Gold, Platinum, Silver and Mercury usually do not react with other elements chemically
to form compounds. These metals are called inactive metals and they are found in nature as the
elements.

But it is mixed with gravel, sand and other soil particals. The has to be seperated from the
impurities. Gold could be obtained from Quart Ore, river sand or gravel as small peices. Here
the most simple mathode to extract the Gold is to sieve the river sand and gravel. Seeving is a
process where gravitational mathodes dependent on dencity. During seeving heavy gold metal
gets collected at the bottom of the vessel and the gravel and sand gets washed out by the mining
wates. Directing the water spout at the gold containes and gold could be extracted.

Another mathod is quarts is powdred and mixed with water , is passed over amalgamated cop-
per electrodes. In this process gold is dissolved at the surface of the plate. Later the Mercury is
bistilled.

A piece of rock which contains gold

77

Competency 3.0 : Use chemical change suitable to fulfil necessity of life

Competency
Level 3.5 : Control the rate of chemical reaction

Activity 3.5 : Let us investigate about the factors affecting the rate of
chemical reaction.

Time : 210 mts.

Quality Inputs : • Spakle, Sandalwood stic and a box of matches
• Four copies of the two page artical on instructions for

exploration given in annex 3.5.1
• Four work station arranged according to instrution given
in annex 3.5.2
• Demy papers and pastels

Teaching Learning Process

Step 3.5.1 • Ignit the Sparkle, Sandalwood stic at the same time and
direct the students to observe.
• Discuss about the students observations.
• Lead a discussion highlighting the following points.
• When Sparkle and Sandalwood stic were ignited the
chemicals present in them burn.
• The rate of burning of Spakle is greater than the rate of
burning of Sandalwood stic.
• There are different factors which could affect the rate
of a reaction.
• The rate of a chemical reaction could be decided by the
time taken to decrease a certain quantity of reactants or
the production of a certain quantity of the product.
(15 mts.)

Step 3.5.2 : • Divide the class into four groups.
• Provide the group with instrutions for exploration, demy
pastels.
• Assign the tasks and engage the groups in exploration.
• Prepare them to present their findings to the class.
(60 mts. )

Step 3.5.3 : • get each group to present their findings to the class.
• Give the first opportunity to the respective groups to
• get the other groups to propose contructive suggestions.
• Summerize highlighting the following points.
• In the experiment it is necessary to keep the factors
constant other than the factor which we are experiment-
ing
• In a reactionwhere a gaseous product is obtained to
determine the rate of reaction the volume of gas liber-
ated at a definite time interval or the time taken to
liberate equal volums of the gas could be measured.

• In the reaction between Magnesium and Acid euqal
weights of cleaned pieces of Magnesium ribbon must
be used.
• When the effect of temperature is determined, equal
sizes of clean iron nails, equal volums of KMnO4,
H2SO4 acidmust be used and the time taken for the
violet colour to disappear must be compaired.
• When acids are used , precautionary measures for safty
must be taken.
• When considering the effect of temperature the differ-
ence in the temperatures of the solutions must be about
150 C .
• When Calcium Carbonate (Marble Chips) are used,
powder or crystals of equal weight must be taken.
• For the Hydrogen peroxide dissociation reaction a
recent production of Hydrogen Peroxide must be used.
• In the experiment to find the effect of concentration on
rate of reaction the set up given below could be used.

Mg ribbon Glass Tube
987654321 987654321
987654321
Rubber 987654321
987654321 987654321
987654321
987654321
987654321 987654321
987654321 H2
Bung 987654321

HCl

987654321
987654321
987654321
987654321
987654321
987654321

(i) (ii) (iii) (iv)

• In the experiment to determine the effect of temperature
on rate of reaction the experiment to be set up as given
below

Cleaned
Iron nail
KMnO4 $H2SO4
Solution

(i) (ii)

0
At room temperature At 60 C temperature

• In the experiment to determine the effect of physical
nature of the reactants the experiment could be set up
as given below.

HCl

CO2
CaCO3

• In the experiment to determine the effect of catalysts the
experiment could be set up as given below

O2

Syringe

H2O2

MnO2 or Sand

(45 mts.)

Step 3.5.4 : • Set up earlier groups and direct them to work stations
• Prepare them to present their findings to the whole class.
(45 mts.)

Step 3.5.5 : • Get groups to present their findings to the class.
• Give the first opportunity for elaboration to respective
groupwhich made the presentation
• Get other groups to propose contructive suggestions.
• summerize highlighting the following points.
• When Mg reacts with HCl with different concentrations,
the time taken to liberate a constant volume of gas de

creased with tthe increase in concentration.
• concentration affects the rate of reaction.
• when Fe reacts with Acidic KMnO4of same concentration,
with increase in temperature the time taken for the violet
colour in the solution to disappear was less.
• Temperarure affects the rate of reaction.
• The time taken for a definit volume of CO2 to liberate when
powdered CaCo3 is less than when the CaCo3 is in the
cryslline form.
• Physical nature of the reactants affect the rate of reaction.
• When MnO2 is used, the dissociation of H2O2 increases.
• MnO2 acts as a catalyst during dissociation of H2O2
• Catalyst affects the rate of reaction.
• A catalyst is a constituent itself undergoing a chemical
change or a decrease in weight.
• When gases reacts if there is an increase of presure the
frequency of gas molecules colliding increase and as a
result the rate of reaction increase.
• It is possoble to control the rate of a reaction as required
by controlling concentration, temperarure, physical nature,
catalysts and pressure.
• Controlling the rate of chemical reactions it is possible to
increase the productivity and efficieancy in day to activities
of chemical production.

(45 mts.)

• Name and explane the factors affecting the rate of a
reaction.
• Accepts the fact that by controlling the factors affecting the
rate of a reaction, the reaction rate could be kept at an
optimum level.

• Set up experiments and test the factors affecting the rate of
chemical changes.
• Conducts activities according to a plan.
• Develope self creations by considering the opinions of
others.
Annex 3.5.1
Instructions for group explorations - handout 1

• Your group is assigned to find the effect of the following factors on the rate of a chemical
reaction.
• Concentration
• Temperature
• Physical state
• catalyst
• Device an experiment to find the effect of the factor using the instrutions and other materials
provides in the work station.
• Be prepaired to present your plan to the class

Instructions for group explorations - handout 2

• Focus your attention to any proposed changes to the plan you submitted.
• Set up apperatus according to plan and carry out experiment.
• Report your observations.
• Get ready to present your findings to class.
Annex 3.5.2

Instrutions to set up work stations

Work station I - Concentration
• 3 pieces of Mg ribbon ( 3 cm )
• Sand papers
• 3 Boiling tubes
• Glass tubing ( about 10 cm)
• Rubber stopper
• HCl solution of 2 mol dm -3, 1 mol dm-3, 0.5 mol dm-3 concentrations
• Stop watch
Work station II - Temperature
• 2 Fe nails
• KMnO4 solution ( 0.1 mol dm-3)
• H2SO4 acid solution (1 mol dm-3)
• Water trough containing hot water.
• Two boiling tubes.
• Measuring cylinder.
• Sand paper
• Thermometer
• Stop watch

Work station III - Physical nature

• Equal weight of Calcium Carbonate crystals and powder.
• Dilute HCl solution
• Conical flask
• Delivery tube
• Rubber stopper
• Thistle Funnel
• Measuring cylinder
• Water trough
• Beehive shelf
• Stop watch

Work station IV - Catalyst

• Conical flask
• Delivery tube
• Hydrogen Peroxide solution
• Manganese dioxide/ Sand
• Syringe ( glass)
• Rubber stopper

Competency 3.0 : Use chemical changes suitable to fulfil necessities of life

Competency level 3.6 : Take steps to prevent metal corrosion

Activity 3.6 : Let us find ways to conserve metal by minimizing corrosion.

Time : 120 mts.

Quality inputs : • Potassium fericyanide and Phenolpthalein
• Small quantity of freshly prepared FeSO4 and NaOH
• 3 copies of artical on instructions for exploration in annex

3.6.1
• 3 work stations arranged according to instructions in annex
3.6.2

Teaching learning
process : • Inquire about their precious knowledge on rusting of iron.
• Add to the freshly prepared FeSO4 solution a few drop of
potassium ferricyanide and a few drop of phenolpthalien to
NaOH solution and show the students.
• Rusting is due to water and Oxygen reacting with Iron
• Acids and salts increase rusting where as bases retard
rusting.
• Initial reactions during rusting could be given as follows.
Fs(s) Fe2+(aq) + 2e (Oxidation)
2H2O(l) + O2(g) + 4e 4OH-(aq) (reduction)
• When Potassium fericyanide is added to a solution of Fe2+
solution there is a deep blue colours.
• Potassium ferricyanide could be used as an indicator to
detect Fe2+ ions in a medium.
• When Phenolphthalein is added to a solution containing
(OH)- there is a pink colour.
• Phenolphthalein could be used as an indicator to detect
(OH)- ions in a medium.
(15 mts.)

Step 3.6.2 : • Divide the class into four groups.
• Provide the groups with instrutiions for exploration, demy
papers and pastels.
• Prepare them to present their findings to the whole class
(60 mts)

Step 3.6.3 : • Get the group to present their findings to the class.
• Give the first oppotunity for elaboration to the respective
group which made the presentation
• Get the other groups to propose constructive suggestions.
• Where the medium turned blue, Iron corrode and forms
Fe++
• Where the medium turned pink, OH- are formed.

Pink Pink
Mg 654321
654321
654321 Zn 7654321
7654321
7654321 Cu 7654321
7654321 Pb 7654321
7654321
654321 7654321 7654321 7654321
7654321 7654321 7654321
7654321 7654321

Pink Blue

• Where the Iron is in contact with metals above Iron the
following occur
• Iron does not corrode.
• The matal which has the higher reactivity acts as the
anode and undergo corrosion due to Oxidation.
• Iron acts as the cathode.
• At the iron nail which acts as the cathode there is a pink
colour due to the production of (OH)- iron.
• These areas are called ‘cathode areas’
• When the metal which has a higher reactivity acts as the
anode and sacrifies itself and prevents iron from rusting,
it is called cathode protection.
eg. applying zink on iron surface. (galvanizing)
• When any two metals in the activity series are in contact
with one another, the metal which has a higher reactivity
corrode protecting the meatal of lower of reactivity
metal which corrodes is called the sacrificing metal.
• When metals which are below iron in the activity series
are in contact with iron the following take place.
• Iron corrodes vigorously.
• Iron acts as the anode and forms Fe2+ by oxidation.
• The blue coloured area near iron nail, which acts as the
anode is called the anode area.
• When a metal is coated to prevent it from coming in
contact with factors which are necessary for corrosion, and
preventing iron from becoming the anode, it is called anose
protection.
eg. coating Iron surface with Sn, paint, grease.

• It is possible to keep the ions formed at the cathode and
the anode by using a jelly medium instead of a liquid
medium in the places where they are formed in a experi
ments where rusting of iron is considered as anelectro
chemical change.
• The process of rusting of Iron could be explained by the
following reactions.
Fe(s) Fe2+(aq) + 2e
2H2O (l) + O2 (g) + 4e 4(OH)- (aq)
Fe(OH)2 (aq) + O2(g) Fe2O3.H2O(s)
• Iron rust is a hydrate Ferric oxide, having a reddish brown
color, a number of water molecules in it vary. As such the
compound is indicated as follows.

Fe2O3.xH2O(s)

(45 mts.)

Criteria for assesment and evalution

• Explain anodic protection and cathodic protection which
prevents rusting of Iron.
• Appreciate that metallic corrosion could be controlled.
• Experiments how metals with different reactivity affect corro-
sion of Iron
• Arrive at inferences from observation.
• Use demostrations as the occasion demands.

Instruction for group exploration Annex 3.6.3

• Your group is assigned to study about rusting of Iron nails
under one of the following conditions.
• When in contact with Mg and when in contact with Sn
• When in contact with Al and when in contact with Pb
• When in contact with Zn and when in contact with Cu
• prepair a set up to investigate the rusting of Iron nails when the
two metals are kept in a jelly medium (Prearation of a jelly
medium is given below)
• Device a suitable control experiment.
Petri dish

43210987654321
43210987654321
43210987654321
43210987654321 Iron nail
43210987654321
43210987654321
43210987654321
43210987654321 Metal piece

Jelly medium

• Forecast what observations you expect to get after one day.
• Take down your observation on the following day.
• Arrive at conclutions about rusting of Iron, considering the
place occupied by the metals subjected to the experiment.
• discuss why it is necessary to use a jelly medium instead of an
aquaious solution, and the jelly medium should not be allowed
to have air bubbles.
• Explain the following phenomena scientifically basing your
conclusion.
• when an Iron bucket coated with Zn (Galvanized) gets
scrached rusting is controlled and could be used for a long
time.
• When food container made of Iron sheet and coated with
Sn get scrached it undergoes rusting very rapidly.

How to prepare the jelly medium

Dissolve a small quantity of NaCl in 250 cm3 of water, add 5g of Agar and while stirring well
boil for about 10 mts. Once the mixture is viscous add 2 cm3 of phenolphthalein, take away
the beaker from the burner stir and when it is some what cool add 1 cm3 of Potacium
ferricyanide and stir further. Before it gets solidified add to petri dishes with Iron nails and
allowed to cool. (See that air bubbles do not get into the jelly). It ispossible to use poedered
sago instead of jelly.

Annex 3.6.2
Instrution for preparation of work stations.

• Keep the following materials and prepare 4 work stations.

• work station - 1 - Three Iron nails (7 cm) , sand paper, 3 petri dishes, Mg and Sn
metal strips 1 piece (size 0.5 cm x 5 cm)

• work station - 2 - Three Iron nails (7 cm), sand paper, 3 petri dishes, Al and Pb

• work station - 3 - Three Iron nails (7 cm), sand paper, 3 petri dishes, Zn and Cu

• Keep at each work station materials required to prepare a jelly medium.

Competency 3.0 : Use chemical changes suitably to fulfil necessities of life

Comptency level 3.7 : Control burning as appropriate to the occasion

Activity 3.7 : Let us look, find out about burning

Time : 120 mts.

Quality inputs : • Three lengh wise folded half sheet papers, so that they are
easily ignited.
• Three copies of instrutions for exploration article given in
annex 3.7.1

• Three work stations arranged according to the instructions
Teaching learning
Process :

Step 3.7.1 • Ignite one of the lengh wise folded papers and cut just below
the flame so that the flame is extinguished.
• Moistened the second paper up to two third of it with
coloured water. Ignite the paper at the dry end and display it
to the students.
• With the third paper leave the ignited end on a sheet and cover
it with an empty jam bottle, allow it to extinguish.
• The flame extinguished as a result of the burning paper
being cut and removed ( combustible subtance isremoved)
• The flame extinguished as a result of the moistend part of
the paper did not reach the temperature required (Ignition
temperature) for it to burn.
• By covering with the jam bottle the supporter of combus-
tion (Oxygen) was prevented from reaching the burning
subtance.
• Three factors essential for conbustion are availability of a
combustible subtance, it should reach the ignition tempera-
ture and the gas which is the supportes of combustion.
• A chemical reaction where a combutible subtance react
with a gaseous supporter of combustion liberating heat and
light is called combustiion.
• During combustion, the carbon and hydrogen in the com
bustible react with Oxygen in the air forming the products of
combustion.
• Paper is manufactured by plant materials which basically
contains carbon and hydrogen.

• During combustion which carbon react with Oxygen,
CO2 is formed and when Oxygen react with hydrogen
H2O is formed.

(15 mts.)

Step 3.7.2 : • Devide the class into three groups
• Provide the groups with instrutions for exploration, demy
paper and pastal
• Assign the tasks and engage groups in exploration.
• Preparee them to present their findings to the whole class.
(60 mts.)

Step 3.7.3 : • Get groups to present their findings to the class.
• Give the first oppotunity for elaboration to the respective
group which made the presentation.
• Get other groups to propose construtive suggestions.
• when a candle is burnin, the solid wax melt and it travels
upwards along the wick and gets evaporated. This wax
vapour gets dissociate due to heat and these react with the
supporters of combustion in the surrounding air and pro-
duce light and heat.
• In the candle flame there are three zones, which could be
observed clearly.
• The inner most zone in the non-luminous zone, it contains a
mixture of wax vapour and air.
• The temperature in the non-luminous flame is low, when
compared to the other zones.
• The zone outside the non-luminous zone is the luminous
zone, here the wax gets dissociated and Carbon monoxide
and Hydrogen gas are produced and start to form Carbon
dioxide and water.
• The tenperature in this zon is higher than the temperature in
the non-luminous zone.
• In the luminous zone, the gases containing Carbon gets
dissociated forming free Carbon particals.
• The Carbon particals get into the incandescent state and
produce the endemic yellow colour of the luminous zone
giving out light.
• The zone outside the luminous zone, at the base of the flame
a blue colour is clearly visible, but at the top it is invisible. In
this invisible zone the remaining Carbon monoxide and
Hydrogen burn.
• In the Kerosene lamp flame,two clearly visible zones, the
non-luminous and the luminous are seen.

• In the wine spirit flame, luminous flame is not visible.

• In the bunsen burner flame, inner most is the non-luminous
zone and outer to that the dark blue and light blue zones in
sequence and outer most is the invisible zone.
• In the bunsen burner at the base the combustible subtance
is made to mix with air and then it is allowed to burn at the
top.
• A combustion reaction in which when there is a supply of
required quantity of Oxigen, the combustion substance
Carbon is completly changed to Carbon dioxide. It is called
complete combustion.
• A combustion reaction in which when there is a limited

supply of Oxigen, part of the Carbon in the combustible
subtance is converted to Carbon monoxide, it is called
parcial combustion.
• In the bunsen burner there is a supply of required quantity
of Oxigen, the fuel undergo complte combustion.
• Apart from three types considered earlier, a flame of a
higher could be got from the bunsen burner.
• When combustion takes place in a limited supply of Oxigen
the unburnt Carbon particals are given out from the flame,
which could be detected as soot by holding a ceremic brick
above the flame.
• When you hold a wire mesh transversely acroos the flame,
due to the absorption of heat by the wire mesh the flame is
not seen above the wire mesh for sometime.
• When yoy hold a glass sheet across the flame in the patch
that forms at the centre unburnt fuel is deposited.
• When you hold a fine metal piece to the outer most zone of
the flame, there is a reduction in temperature and as a result
there is partial combustion and turns luminous for a short
time.
• When you bring a flame to the vapour of an extinguished
flame soon after it was extinguished, the vapour catches
fire.
• In ovens where there are methods to control the supply of
Oxigen and fuel, it possible to obtain a flame which shows
complete combustion, with no soot but producing a higher
quantity of heat.
• When products of combustion are sent through anhydrous
Cpper sulphate there is a blue colouration which confirms
that there is production of water vapour during combustion.
• when the products are sent through lime water, the milki
ness shown confirms the production of Carbon dioxide
during combustion.
(45 mts.)


• Name the zones in the candle flame and explain their nature.
• Appreciates that combustion could be controlled depending on
its requirment.
• Observe the nature of a flame by simple experiment.
• Explane observations scientifically.
• Shows interest in the protection of one’s self, the others and
the environment.


• Your group is entrusted to find the nature of one of the flames.
• Flame of oil lamp.
• Flame of spirit lamp.
• Flame of Kerosene lamp.
• See whether the zones visible in the candle flame and in the
bunsen flame are visible in the flame provided to you.
• Engage in the following activities using the flame provided to
you.

• Holding a piece of ceremic brick to the flame horrizontally
above the flame for about 10 seconds.
• Holding a wire mesh horrizontally across the flame.
• Holding a glass slide horrizontally for about 2 sec. across
the flame.
• Introduce to the thin colourless outr zone of the flame the
end of a thin wire.
• Extinguish the flame and immediately hold the flame of an
ignited splinter close to the wick.
• Find the time required for 20 cm3 of water in a boiling tube
to boil.
• Compare the nature of the flame provided to you with the
flames of firewood hearth, Kerosene oil cooker and a gas
oven.
• In the instances given above the fundermentel components
elements present in the fuel are Carbon and Hydrogen. The
following set up is provided to you to undestand about the
products of combustion in the flame.

• Discuss in the group the equipment to be used, procedure
to be adopted and observation expected.
• Be prepared to present your findings to the class.

Annex 3.7.2

Instrution setting up work station

• Keep the following materials and set up three work stations.
• Piece of ceremic brick
• Copper wire guage
• Glass slide

• Piece of wire 20 cm long.
• Box of matches
• Candle stick
• In the above work stations, in the first keep coconut oil lamp in the second spirit lamp, in th
third Kerosene oil lamp.
• Display a burning bunsen burner for all the students in the class to observe.

Competency 3.0 : Use chemical changes suitably to fullfill necessities of life

Competency Level 3.8 :Shows awareness in extinguished fires
Activity 3.8 :
Prevent fire accidents'
Time :120 mts'
Quality inputs :• Incident on ,"Hoe fire became a foe to me" in
annex 3.8.1
• Three cop[ies of instructions for group exploration given
in annex 3.8.2
• Instruction for arrangement of work stations given in
annex 3.8.3

• Artical in annex 3.8.4 on " Let us not fall prey to fire"
• Demy and pastals
Teaching- learning process :
Step 3.8.1 : • Get a student to precent the incident to class.
• The possibility of causing fires due to unprotected
bottle lamps.
• It is possible for accidental fires to cause deaths or
bodily problems for life times.
• When a person who had caught fire to his cloths
run, the supply of Oxygen is better and as a result
could develop further.
• When clothes catch fire , it is possible to controll the
fire by wrapping the body with a gunny bag or a
thick clothe.
• Fire gets extinguished when one or more factors
shown by the fire trangle are removed.
at

O
He

xy
-

Fuel

(15 mts)

94

Step 3.8.2 • Divide the class into three groups.
• Provide the groups with exploration instructions , the artical, demy
paper and pastel.
• Assign the tasks and engage the groups on exploration.
• Prepair them to present their findings to the class.

(60 mts)
Step 3.8.3 • Get the groups to present their findings to the class.
• Give the first opportunity to the respective group to eleborate on
the presentation.
• Get other groups to prepare constructive suggestion.
• Summarize highlighting the following points.
• Fiires are grouped as follows in order to make it easy to

select the the correct fire extinguisher for the respective fire.
• A grade fires - Fires associated with Carbonic compounds
like wood, clothes, paper etc.
• B grade fires - Liquids with highly inflammable like petrolium
products, paints, wax, copra, plastic,
polithene and grease etc.
• C grade fires - All gasses which are inflammable, like
acetylene, L.P. gas, propane, butane etc.
• D grade fires - Fires from metals like Sodium, Potassium
Magnesium etc.
• It is possioble to use water fire extinguisher for A grade fires.
• Soda - Acid fore extinguisher for A grade fires.
• Foam fire extinguisher could be used for B grade fires.
• Carbon dioxide fire extinguisher especially suitable for B and C
rate fires, and when required for A grade fires.
• Halon fire extinguisher could be used for all grades of fires.
• Especially for D grade fires and sometimes for C grade fires
( Dry powder ) fire extinguisher could be used.
• Water or foam fire extinguisher are not suitable for fires which
has a electricity leakage or where there is a possibility of an
electricity leakage.
• The supply of electricity must be disconnected before any
attemp is made to extinguish a fire where there is an electricity
leakage or where there is a possibility of an electricity leakage.
• In the experimental fire extinguisher water with Carbon dioxide
under pressure comes out of the fire extinguisher where Sodium
bicarbonate and dilute Sulphuric acid reaction is used.
• In the experimental fire extinguisher where Sodium bicarbonte
and Aluminium sulphate reaction is used, the foam comes out
under pressure.
• In the experimental water fire extinguisher a jet of water under
pressure comes out.
(45 mts)
95

Critaria for assesments and evalution.

• Explane types of fires, instructions for extinguishing fires, instance where there suuitable for
use.
• Appreciates the fact that the fire extingusher must be chosen depending on the type of fire.
• Construct a simple working model of a fire extinguisher.
• Shows a tendency to protect from accidents.
• Learn from experiances of others.

Annex 3.8.1

How fire became a foe to me

I am Acvhala. From my small days I had the habit of getting up early in the morning and
helping mother. As we did not have electricity in our house we used bottle lamps. On this unfor-
tunate day too I got up in the morning lighted the oil lamp. When I was going to the kitchen to
ignite the hearth the bottle lamp fell erom my hand. The kerosene oil get smeared and the flame
extended. Mt clothes caught fire. When I was shoutiung and running about the flae increased
further. Fortunately I fell down. Mother came running and wrapped me with a gunny bag. Al-
though the flames extinguished I was unconseious. I regained consciousses at the hospital. My
hands, legs and face were burn. When I recovered I was left with a folded skin and some big
scars. Whenever I see them it gave me a great pain. I related this story to you, young sisters and
brothers, to redused my pain and also to tell you about how important it is to protect yourself
from fires.

Annex 3.8.2

Instruction for group exploration

• Draw your attention to the incident assigned to you from the following.
• To extinguish of small fire in the stationery stores of the office using the Soda Acid fire
extinguisher.
• Extinguishing a spreading fire in a fuel filling stations using a foam fire extinguisher.
• To controle a fire in carpentry shop using water fire extinguisher.
• Disscus the principal of the allocated fire extinguisher and also how the fire is extinguished.
• Arrange the set up of the fire extinguisher allocated to you by using the instruments and the
materials provided in work stations.
• Be prepared to present to thre class about the activity of the fire extinguisher you set up and
your findings you discover.

96

Annex 3.8.3
Instruction for setting work stations

Work station - I

Bottle with a large mouth and a stopper to fit with a single hole
Small bottle without a lid
A delivery tube bend in shape L, with a jet at the end of it to fit the hole in the stopper
Dilute sulphuric acid
Consentrade solution of Sodiuim bicarbonate
Clay pot to burn a fire
Box of matches
Pieces of paper fit to burn

Piece of jute thread
The diagram

Dilute Sulphuric Acid

Sodium bicarbonete solution

Work station - II
Bottle with a large mouth and a stopper to fit with a single hole
Small bottle without a lid
A delivery tube bend in shape L, with a jet at the end of it to fit the hole in the stopper
Solution of Aluminium sulphate
Solution of Sodium bicarbonate
Clay pot to burn a fire
Box of matches
Small quantity of kerosene oil to burn
Piece of thread
The diagram

Aluminium sulpahte
solution

Sodium bicarbonete solution

97

Worl station - III

One inch PVC pipe about 25 cm
A lid or endcap to close the end
3/4 inch wooden handle slightly longer than 25 cm
Bottom of an old slipper
Sharp knife
Some PVC gum
One inch Iron nail
Small hammer
A clay pot to burn a fire
Box of matches
Wood which ignite easily

The diagram

Annex 3.8.4
" Let us not fall prey to fire"

Fire is very essential to man but also it is distructive. Three conditions are necessary for
fire to burn. There are , a combustible subtance, heat energy required for it to burn and Oxygen.
When a fire is destructive it must immediatly extinguished. For this one or more factors given
about must be removed. Fire extinguishers are manufactured for this. All fires cannot be extin-
guished from a single fire extinguisher. Because of this in order to select the best fire extinguisher
the fires are grouped.

A - grade fires
This includes fires caused by materials with contains carbonic compounds like wood, cloths,
paper etc.

B -grade fires
This includes fires caused by materials which are highly imflammable liquids, or liquids
petrolium products, paints, wax, copra, plastic, polythene, grease etc.

C - grade fires
This includes fires caused by all inflammeble gasses like Acetylene, LP gas, Propane, Butane
etc.

D - grade fires
This includes fires caused by metals like Sodium, Potassium, Magnesium etc.

98

Water fire extinguisher is used in the case of A - grade fires. A large quatity of water is blown
to and it behaves as an artificial rain and falls on the whole burning systems. As a result of the
water absorbing heat from the combustible subtaince the fire is extinguished. For small scale fires
manually controlled water fire extinguishers are used. In these water is kept at very high pressure
using Carbon dioxide or Nitrogen.

Soda - Acid fire extinguisher can be used to extinguish A - grade fires. It is arrange in a way
that the Sodium bicarbonate and dilute Sulphuric acid are kept in seperate cylinders. When these
two subtances get mixed water and Corbon dioxide are forced out at high pressure. As a result
of Carbon dioxide the fire is prevented from gettin the gas which supports combustion.

Foam fire extinguisher is especialy designed to extinguished B - grade fires. In the foam fire
extinguisher thre is artificially prepared foam. When foam at high pressure falls on oil it floates

and prevent the combustible suntance coming in contact with the supporter of combution Oxy-
gen.

Carbon dioxide fire extinguisher is manufactured by storing liquid Carbon dioxide at high
pressure. In case of a fire the liquid Carbon dioxide is directed on to the fire. By useing this fire
extinguisher A,B and C grde fires could be extinguished. When using this fire extinguisher it must
be used in such way to prevent accidents to the person who is using the equipment and the
people who are in the fire from inhale Carbon dioxide gas.

Halon fire extinguisher is good to extinguished all fires. It has Nitrogen gas mixed with Halon
and liquified. This gas cool the combustible substaince , and the suppoter of combution is pre-
vented from reaching it. A special significance of this fire extinguisher ther is no left over of
anything given out from the extinguisher.

Dry fire extinguisher the chemicals subtance used in this are Potassium bicarbonate, Sodium
bicarbonate, Ammonium phosphate and Ternary Eautetic Chloride powder. In this case when
the dry powder is directed to the fire the chemical reaction in the flame stops, prevent the com-
bustible subtance from reaching the ignation temperature. The superter of combution is pre-
vented from coming into contact with the combustible subtance, the flame is extinguished.
The fire extinguisher is specially suitable for D grade fires and sometimes for C grade fires.

99

Competency 3.0 : Use of chemical changes suitable to fulfil necessities of life

Competency level 3.9 : Produce a gas - Examine its properties.

Time : 120 mts.

Quality inputs : • A baloon filled with H2 gas, according to instructions given in
annex 3.9.1. and an empty baloon.
• Three copies of article on instructions for exploration given in
annex 3.9.2
• Work stations arranged accordind to instructions given in

annex 3.9.3
• Demy papers and pastel

Teaching learning
process :

Step 3.9.1 : • Take the baloon filled with H2 gas, to the class. (do not
mention that it contains H2 gas)
• Give the other baloon to a student and instruct him to blow into
it so that it is of the same size as the H2 filled baloon and tie it.
• Let the students predict as to what would happen when the
two baloons are released from hand, direct them to observe.
• Both baloons contain the same volume of gas.
• One baloon contain H2 gas.
• The other baloon has expired air.
• H2 gas is less dense than normal air, as a result the baloon
went up.
• Expired air is more dense than normal air, as a result the
baloon went down.
• Different gases have different physical and chemical
properties.
(15 mts)

Step 3.9.2 : • Devide the class into three groups.
• Provide the groups with instrutions for exploration, demy and
pastal.
• Prepare them to present their findings to the class.
(60 mts.)

Step 3.9.3 : • Get the groups to present their findings to the class.
• Give the first oppotunity to the respective groups to elaborate
on their presentation
• Get the other groups to propose contructive suggestions.
• Summerize highlighting the following points
• H2 gas has the following properties.
• Colourless
• No smell
• Lighter than air
• Slightly soluble in water
• Doesnot change the colour of moist litmus paper
• Burn with a ‘pop’ sound when a burning splinter is
introduced

• No colour change with lime water
• It is possible to indicate the chemical reaction between Zn
and dilute HCl by the chemical equatiion given below.
Zn(s) + 2HCl(aq) ZnCl2 + H2(g)

•O2 gas has the following properties.
•Colourless
•No smell
•Heavier than air
•Slightly soluble in water.
•Doesnot change the colour of moist litmus paper.
•when a glowing splinter is introduced it burns rapidly.
(suporter of combustion)
• No colour change with lime water.
• The production of O2 gas by the dissociation of H2O2 by
MnO2 is given by the chmical equation given below.
H2O2(aq) 2H2O(l) + O2(g)

• CO2 gas has the following propeties.
• Colourless
• No smell
• Heavier than air
• Slightly soluble in water
• Moist blue litmus paper turns pink
• Extinguish a glowing spliter
• Turns lime water milky ( when more gas is bubbled
through the solution become colourless)
• The chemical reaction which produce CO2 by reacting
CaCO3 with dilute HCl is given by the equation given
below.
CaCO3(s) + 2HCl(aq) CaCl2(aq) + CO2(g) + H2O(l)

(60 mts.)


• State the properties of O2, H2 and CO2 gases.
• Appreciates that gases have varying properties.
• Tests the properties of gases.
• Prepare a set up illustrated by a diagram
• confirms identity by properties.

Annex 3.9.1

Getting a baloon filled with H2

Baloon with H2

Tub
Bottle

NaOH solution o Water
o
o
o
Pieces of Aluminium

Annex 3.9.2

Instrutions for group exploration

• Your group is assigned to produce one of the gases given below and find its’ physical and
chemical properties.
• Oxygen gas
• Hydrogen gas
• Carbon dioxide gas
• Using the materials placed in the respective workstations, instruments and the diagram
prepare a set up to produce the gas assigned to you.
• Conduct the following tests to understand the properties of the gas.
• Introduce into the gas a glowing splinter with the flame extinguished
and a glowing splinter with the flame.
• Hold to the gas moistened blue and red litmus papers.
• Bubbling the gas throuh lime water.
• State your observation in each of the instances.
• Arrive at conclusions about the properties of the gas from your observations.
•Be prepared to present your findings to the class.

Annex 3.9.3

Instructions to set up work stations

• Prepare three workstations and provide with materials necessary to set up an experiment as
given in the illustration below.

Delivery tube

Thistle funnel

Gas jar

Conical flask
Trough
Beehive shelf

Water

• Provide each workstation with a illustration of the experiment, two test tubes, lime water,
Red and Blue litmus papers, splinters and box of matches.

Work station - 01

• MnO2
• H2O 2 Mno2
• 2H2O2 (aq) 2H2O(l) + O2(g) (In a display board)

Work station - 02

• Zn turnings
• Dilute HCl acid
• Zn(s) + 2HCl(aq) ZnCl2(aq) + H2(g) (in a display board)

Work station - 03

• CaCO3
• Dilute HCl acid
• CaCO3(s) + 2HCl(aq) CaCl2(aq) + CO2(g) + H2O(l)
(In a display board)

Competency 3.0 : Use chemicals reaction appropriately to fulfil requirments
in life.

Competency level 3.10: Investigates experimentally changes in heat associated with
chemical reactions.

Activity 3.10 : Let study the changes in heat associated with chemical changes.

Time : 120 mts.

Quality input : • Two test tubes, two glass rods, 2g each of Glucose and

Sodium hydroxide
• Four work stations arranged according to the instrutions given
in annex 3.10.1
• four copies of instrutions for exploration given in annex 3.10.2
• Demy papers and pastel

Teaching - learning
process :

Step 3.10.1 : • Get two students in front of the class and give a test tube with
water and a glass rod to each.
• Provide one student with some Sodium hydroxide and the
other some Glucose and allow them to dissolve them in the
water and instruct them to report to the class any observations
about change in temperature.
• Conduct a discussion highlighting the following.
• Temperature of the solution increased when Sodium hy
droxide was dissolved in water.
• Temperarure of the solution decreased when Glucose was
dissolved in water.
• Change of heat ia associated with chemical changes.
• It is possible to calculate the change in heat by using change
in temperature of the solution.
• If the change in temperature is q , mass of the solution in m
the specific heat capacity c , the heat change is Q is
expressed by the equation,
Q = mcq
• The specific heat capacity of water is 4200 kJ0C-1kg-1
• Mass of 1 cm3 of water is 1 g,
(15 mts.)

Step 3.10.2 : • Devide the class into four groups
• Provide the groups with instrutions for exploration, demy
paper and pastel
• Assign the tasks and engage groups in exploration.
• Prepare the groups for whole class presentation.
(60 mts.)

Step 3.10.3 : • Get the groups to present their findings to the class.
• Give the first oppotunity for elaboration to the respective group
which made the presentation.
• Get the other groups propose construtive suggestions.

• If heat is given out during a chemical reaction the tempera-
ture of the reacting mixture increase.
• Reaction which liberate heat during reactions are exother-
mic reactions.
• If heat is absorbed during a chemical reaction the tempera
ture of the reacting mixture decrease.
• Reactions which absorb heat during areaction are endother-
mic reactions.
• In an exothermic reaction, the energy in the product is less
than that of the reactants.
• In an endothermic reaction the energy in the products is
more than more than that of the reactants.
• It is important to use quatities of reactanta which show
practically measurable temperature difference.
• In this experiment we hypothesize that,
• The entire quantity of heat associated with the reaction
was used to change the temperature of the reacting
mixure.
• Heat capacity of solutions is equal to the heat capacity
of water.
• The density of the solution is equal to the density of
water.
• Change of heat calculated in a reaction, change with the
physical nature of the product and reactants.
• Therefore when change of heat associated with a reaction is
stated it is necessary to indicate the physical state of reac-
tants and products.
• To observe a maximum change in temperature the loss of
heat to the enviroment must be minimized.

• Loss of heat could be minimized by conducting the experi
ment in an insulated vessel.
• To allow the reactants to mix well, the mixture should be
stirred with a stirrer/glass rod.

(45 mts.)

• Explane with examples, exothermic and endothermic reactions.
• Appreciates that there ia an exchange of heat associated with chemical reactions.
• Determine experimentally the heat change associated with chemical reactions.
• Reach conclusions based on hypothesis.

• Investigates the accuracy of conclusions.

Annex 3.10.1
Instructions to prepare work stations

• Have the following set of materials in all the work stations and also specially mentioned items
in the respective work stations
• Thermometer
• 100 cm3 beaker
• Stirrer or glass rod.

Work station - 01

• 50 cm3 of HCl solution (add 8 cm3 of concentrated HCl up to 50 cm3 of water)
• NaOH pellets 1g

Work station - 02
• 50 cm3 of CuSO4 solution (dissolve 5 g of CuSO4 salt in 50 cm3 of water)
• Fe powder 1 g

Work station - 03
• 50 cm3 of H2SO4 ( add 3 cm3 of conc. H2SO4 to 47 cm3 of water)
• Clean Mg pieces 0.5 g

Work station - 04
• NaHCO3 2g
• Citric acid about 50 cm3 (dissolve 5g of Citric acid in 50 cm3 of water)

Annex 3.10.2

• Draw your attention to the following chemical reactions assigned to your group
• NaOH(s) + HCl(aq) NaCl(aq) + H2O(l)
• CuSO4(aq) + Zn(s) ZnSO4(aq) + Cu(s)
• H2SO4(aq) + Mg(s) MgSO4(aq) + H2(g)
• NaHCO3(s) + Citric acid (aq) Sodium citrate (aq)+ CO2 (g)
+
H2O(l)

• Go to your work station and device an experiment to conduct the allocated reaction to

determine the heat change.
• When handling chemical subtances be careful about the dameges to you and the others.
• Calculate the change of heat associated with a molecular mass of the solid state reactant
used.
H=1 Na = 23 Cl = 35.5
C = 12 Mg = 24 Zn = 65
O = 16 S = 32 Cu = 63.5

• Discuss about the following points.
• Errors in the experiment.
• How to minimize errors.
• Hypothesis used in calculations.

• Be prepared for a presentation of your findings to the class.

Competency 3.0 :Use chemical changes in an appropriate way to
fulfil living requirments.

Competency level 3.11 :Investigates how weathering of rocks help in the
formation of soil
Activity 3.11 :Let us Investigates how weathering of rocks help in the
formation of soil
Time : 120 minutes
Quality inputs : • Small pieces of granite,quartz,limestone,mica
• Three copies of instructions for exploration given in

annex 3.11.1
• Three copies of the article"Earth and rocks"
• Demy papers and pastels
Teaching-learning process :
Step 3.11.1 : • Small pieces of granite/quartz,limestone and mica are
distributed among the students and directed to observe
them.
² Inquire from the students how the substances provided
as well as similar substances are subjected to change
Conduct a discussion to highlight the following points.
That,
² According to observations ,in the piece of granite there
are black coloured and shining components are
included in different quantities.
² The piece of granite is a heterogeneous mixture.
² According to observations quartz,limestone and mica
pieces shows homogeneous nature.
² A mineral is a crystalline non carbonic substance which
is homogeneous and having a definite geometric shape
and a definite compossition.
² A heterogeneous solid mixture without a definite
compossition and a geometric shape and made up of a
number of minerals is called a rock.
² Due to physical,chemical and biological activities
minerals and rockes change into different types.
(15 minutes)

² Provide the groups with instruction for exploration the
article,demy papers and pastel.
(60 minutes)

tions,

That,
² It is possible to distinguish three types of
rocks, igneous,Sedimentary and metamorphic
rockes.
² Igneous rocks are formed from cooling magma
coming from the interior of theEarth.
Eg. Basalt.
² Magma coming to the surface of the earth from
empting volcanoes is subjected to rapid cooling
,forms igneous rocks,which are made up of small
crystals.
Eg. Granite
² Magma which cools slowly inside the earth forms
igneous rocks with big crystals.
² Igneous rocks are very hard and there is indication to
show that they are deposited as layer or grains.
² Weathering of hard rocks result in mineral and
carbonic substances which are deposited as layers at
the bottom of reservoirs.
² When sedemented layers at the bottom are subjected
to pressure from layers above,Sedimentary rocks are
formed.
Eg. Mudstone,Conglomerate
² The Sedimentary rocks are not as hard as igneous
rocks.
Eg.Limestone

• When igneous and sedimentary rocks are subjected to
temperature,pressure and movement of the surface of
the earth,their nature changes and form metamorphic
rocks.
Eg Marble,slate
• Nature of Metamorphic rocks differs according to the
original rock from which it was formed.
• Breaking down of rocks expossed on the surface of the
earth into small parts due to physical,chemical and
biological factors is called Weatherning of rocks.
• Rocks are subjected to physical Weatherning due to
Sun,rain,wind and ice.
• Chemical Weatherning of rocks is when a rock is
subjected to a chemical change where compounds in
it are changed to simple compounds.
• Due to some activities of living beings on rocks,both
physical and chemical weatherning takes place.
• Soil is formed when sand and clay formed from
Weatherning of rocks combine with Organic matter
from plants and animals.
• Formation of rocks,and they under go weatherning and
form soil ,occur as a cycle in nature.
• Rocks in earth undergo changes from one from to
another in a cyclic movement.
(45 mts)

² Explain how soil is formed from weatherning of rocks.
²Appreciates that rocks undergo changes in a cycle.
² Observe diversity in rocks..
²Collect data from sources.
² Present data in an attractive way.

Annexe 3.11.1
²Your group is assigned to investigate how one type of rock is formed and how one factor
help in the weathering of rocks.
• Types of rocks according • Factors help in
to how it is formed weatherning of rocks
• Igneous rocks • Chemical factors
• Metamorphic rocks • Physical factors
• Sedmentary rocks • Human and other biological
factors

² Discuss in the group about the type of rock you are assigned to you and about the factor
that help in the weathering of rock.
² Be prepared for a creative presentation of your findings.

Annexe 3.11.2
Earth and Rocks
The day for which Anil,Upul and Namal were eagerly waiting for arrived. the three showed
a keen interest for Geology. It was for no other reason but the teacher was able to make the
classroom interesting by engaging them in various activities to arouse the interest of the
students.The trip was organised to educate them about geological resources.
Anil started the discussion by stating that"Man`s curiosity about minerals started from the
time he found that implements could be made by stones."But man used pieces of stones to
make stone implements.Rocks found nature are stones which are a combination of one or
mo
Teacher introduced his friend, geology Professor.He spoke to the three students and said,
"Our country is full of resources.out of these resources Geological resources occupy an
important place.Only a minute fraction of it could be found during this trip."
As the vehical was moving he showed a granite rock and said,early man may have made
implements from these.The granite rocks they used to make implements belong to the igneous
rocks.In Latin `Ignis`means fire.At a depth of more than 30km from the surface of the
earth,the rocks get liquietised or fused due to high temperature.This liquid is known
as`Magma`When this magma comes to the surface of the earth during volcanic eruptions,it is
called `lava`.When this lava gets cooled and solidified igneous rocks are formed.It is possible
for this lava to cool inside the earth and form igneous rocks.

In addition to granite,basalt,rhyolite and obsidian are examples for igneous rocks explained the
Professor.
At the moment the vehicle was going along a road .which was constructed recently after
cutting a hill. The Professor instructed the vehicle to be stopped. Professor said"Let us get
down from the vehicle,I will show you something". All of us walked behind the Professor.
"Can all of you see clearly the layers deposited in this cross section of the hill.Any rock which
is regularly exposed to factors and agents like high heating,high cooling,Sun,Rain,Acid rain
breaking up due to water and wind break up into small particles.This process is called
weatherning of rocks".These settle as logitudinal layers on the surface of the earth,or at the
bottom of resoviors or ocean.These layers are called sediments.If these layers are arranged
loosely they occur as gravel,sand on the sea shore and sand dunes,when futher sedimentation
on top of these,occur the weight of these layers cause the particles to get tied together and
form into rocks.These are called `sedimentary rocks`.Mudstone,Conglomerate and Siltstones
are examples for sedimentary rocks.sometime animal bones and dead bodies of micro organ
sms with calcareous(calcium carbonate) shells gets deposited for millions of years forms a
sedimentary rock.,the limestone.These deposits are seen in the Jaffna peninsula and north of
Puttalm,said the teacher,joining the discussion."Does laterite stones (Kabok) belong to the
i
sedimentary rocks"asked Upul. No.we do not consider it as a sedimentary rock because it
has been found that laterite is a product of some type of largely weathered rock which include
clay.
When this discussion was going on with the Professor important was taken down in the
field note book.
The group got into the vehocle and restarted the field trip." In Marshy places and in
forests with trees, the dead animals and plant materials get collected on the soil. They under go
changes and after millions of years forms coal." questioned Anil
"Son, you raised a very good question."
When dead plant and animal matter which is carbonic matter is added to the soil it is decom-
posed by microorganisms. sometimes,soft and brown coloured peat is formed from these
carbonic material after a long period. In our country peat is found in Muthurajawela.When
peat inside the earth is subjected to pressure by the layers collecting on top of it,and high
temperature,coal is formed after is long period of time.Since coal is a carbonic material it is not
grouped under as either a mineral or rock.But some scientists include coal as carbonic rocks
under sedimentary rocks.This Process occur in lakes,resoriviors or marshy or Brakish water
having environments explained the professor.
Then upul asked that in addition to igneous rocks and Sedimentary rocks,their is metamorphic
rocks.

The high temperature and pressure inside the core of the earth or movement of the earths`
crust or chemical action with other substances and gases rocks undergo changes.

As a result of this rocks become metamorphic rocks,explained the teacher.
During these change,the mineral composition or the texture(what you see on the surface and
what you feel when you touch it with your hand) of the rock or both could change.For ex-
ample when limestone gets metamorphed it changes to marble said the Professor.
Further examples of this are greiss,slate, and quartzite.As namal said at the begining,any type
of rock turns to liquid magma at the core of the earth.where the temperature is about 6600C.
That is correct,as magma inside the earth comes to the surface,it is called lava.Igneous rocks
are formed from magma or lava.
When we look at rocks this way I feel that there is cyclic movement among rock types.
"I wanted to explain this fact.Any type of rock on the surface of the earth undergo weathring
gets deposited as layers and form sedimentary rocks.Similarly rocks into metamorphic rocks
due high temperature,pressure and various chemical changes.The rocks in the core of the earth
gets liquified or fused and form magma and in the end form igneous rocks.In this way igneous

rocks,Sedimentary rocks,and metamorphic rocks changes from one to the other in a cycle.
This is called the rock cycle said the Professor.
Heard in another place.
This is the containing rocks.In each of these cubicles there is a different type of rock,give
the piece of rock named granite.This is not granite,it is different.This was brought from
Scotland.It is dark in colour.Its` crystals are very fine.When lava gets cooled suddenly this
high quality granite is formed. How about granite in our Country?
According to the data discovered by Scientists there is no pure granite in Sri Lanka.
But their are ancient stone pillars which are thousands of years old,we see them as if they were
built today.
Let me see the facts you wrote?The Professor started to read what they had written.
Ah.Here is the section written about weathering of rocks.
`yes`
Very good.Children this is the challange I give you.By refering to different resource material
construct an article on"the different ways of weathering of rocks".I give you two weeks from
today.There is a Valuable present for the best article and it would be published in the
Magazine.

Identify the charactors of following rocks

Sedimental
rocks
Eg. Sandtone

Metamorphic
rocks
Eg. Schist

Igneous
rocks
Eg. Granite

T

The three friends collected data from various electronic and printed media in addition to facts
collected during the trip.not only that,they collected data from books written by Srilankan
Scientists,and also from compact discs of diffferent encyclopedias and tried to present a
resourseful artical. The Artical submitted by Upul got the frist place.It was presented in the
following manner.

Rocks break up-Soil is formed

Rocks,which is earths` heritage regularly changes due to various factors and form soil. This
Process is known as weathering of rocks.

Physical weatherning of rocks

Due to various factors the rocks on the surface of the earth break up into small parts which is
physical weathering.Heat of the Sun,water,wind are the factors which cause physical
weathering.
a) Exporsure of rock to sunlight
The top layers of the rocks exposed to sunlight gets dried up.This is due to Sun`s heat.During
rain it gets wet.The volume of the rock increase when it is hot and decrease when it is
cold.When this process is repeated there is weathering of the rock.

wõfjkqhs
jeiafikqhs ug
yß u lrorhs

Example.Shalka gal is a sedimentary rock. It is formed by layers arranging one on top of the
other.These get regularly dried up and wet,they undergo weathering,as a result the layers of
the rock break up and ultimately from small partices.

b) Rocks dissolve in water
When rocks come in contact with water,some minerals in it gets dissolved.As a result the
structure of the rock gets weak.Because of this the rock breaks up.
When carbon dioxide is dissolved in water it is acidic,this cause weathering to take place
faster.

c)Heating and cooling of rockes
Rocks are exposed to Sun during daytime.They undergo expansion due to Sun`s heat.At
night the rocks get coooled and as a result undergo contraction.Rocks made up of a number
of different minerals undergo weathering in this manner.Different minerals have different
coefficients of expansion.As a result the bonds between minerals in the rock become less.This
causes the surface of the rock to crack.This makes it easy for the rock to break up into small
parts.Water getting into the cracks is also a cause for weathering.
d)Sand brought by winds
When there is a heavy wind,the sand in the sea,and the rivers gets carried by it.When these
sand particles strike the rock small particles of it break off.
e)There is physical weathering due to rock particls striking one another in rivers and canals.
The pieces of rocks in rivers and canals become rounded due to parts of it getting removed.
f)Rain water could enter into the crackes in the rocks caused by various reasons.During the
winter season the water in the crackes turn to ice.The volume of ice is bigger than that of

water.As a result the crack gets bigger.This causes the rock to split up.Big rocks spilt up into
pieces in this way.

Water gets
collected When Ice With time
in the crackes water the rocks
turn to ice breaks up
there is

crack
gets
bigger
Temperature falls
below 0 0 C

Due to hot and cold climate
big rocks break up into small pieces.

Chemical weathering of rocks
Rocks undergo chemical weathering due to the effect of various factors on rocks.The chemical
substance cause interaction with the rocks.As a result chemical changes occur in the rocks
forming simple compounds.Here oxygen,water,and acidic substances behave a agents of
weathering.These reacton takes place very slowly.

• The oxygen in the air,reacts with
minerals which go to form the rock,as
a result the rock undergo chemical
weathering.
For example as result of the iron
present in rocks,the rocks undergo

weathering.
Oxigen in the air cause Iron in the
rock to corrode
• Formation of new compunds due to the reaction between the rocks and water is called
hydration.Hydration too cause weatherning of rocks.
• The minerals present in the rocks,sometime undergo hydrolysis.Minerals like Sodium ,
Potassium,Calcium,Magnesium,Aluminium and Iron undergo hydrolysis.
Example:- Hydrolysis of Orthoclas rock yeild Clay.
• When Carbondioxide is dissolved in rain water a weak acid is formed.(This is called
Cabonization.) This acidic water interacts with minerals in the rock.Here the carbonate of
the mineral is formed.This also cause weathering of rocks.

Eg:- Limestone is weathered
by carbonic acid eventually
cavems are formed

• In a soil where there there is decay of carbonic material by micro organisms the
carbondioxide gas is very high.This is because of the activity of microorganisms on the
decaying carbonic material.When this carbondioxide,dissolved in water interacts with
minerals in the rocks carbonates of the minerals is formed.This cause the weathering of
rocks.
• You must have seen white,light green,light blue patches growing on rocks.These patches are
symbiotic unions between algae and fungi.They are called Lichens.Secretions emitted by
these Lichens cause weathering of rocks.
• During Lightening, the nitrogen and oxygen react forming nitric oxide and nitrous oxide.These
gases dissolve in rain water nitric acid and nitrous acid are formed.Rain water with these
acids dissolved is called acid rain.These acids,when they fall on rocks cause weathering.

Weathering of rocks by living beings

• Living beings,living the same enviroment as the rocks,contribute to the weathering of rocks.
When roots of a plant close by grow into a split in a rock caused by physical weatherning
the split gets enlarged and the rock is split up.If not,If there is a crevice formed due to
chemical weathering which is suitable for plants to grow the roots of the plants increase the
split.

These tree rots have broken of pieces of
rocks
• Man cause weathering of rocks by breaking then up.
• When micro organisms grow on rocks the chemicals they emit cause weatherning of rocks.
• The lichens that grow on partially weathered rocks,physically or chemically,cause the
weathering of rock.
• Some animals which live associated with rocks dig up the soil around the rock.when rain
water gets collected in it cause weathering of the rock.
Eg:-Animals dig the soil around the rock.The water that is collected in these places cause
weathering of the rocks.
• When hooves and horns of animals are periodically rubbed or struck against the rocks,the
rocks get worn out.
• Reactions caused when excretons matter of animals gets collected on rocks,there is weath
ering of rocks.

Rock cycle

Igneous IGNEOUS rock is weathered
(extrusive) and carried to the sea by revers

Igneous
(Intrusive)
Sea

METAMORPHIC
Magma SEDIMENTARY
rock

rock
Earth movements
Rock is squash and bury
melted
the layers of
sedimentry rock

According to the states of cartoon nos. (1),(2) and (3) understand the above rock cycle
number (1),(2),(3).

Tools for Extended Teaching - Learning Process

1'0 Evaluation State ( Term 2, Tool 1
2'0 Competancy Levels covered ( 1'1" 1'2" 1'3" 1'4
3'0 Subject content covered ( ² Atom
² Sub Atomic particals
² Model for Atomic structure
² Atomic number
² Mass number
² Isotops

² Electron configuration
² Relative Atomic Mass
² Chemical bonds
² Chemical formula for Molecules
² Relative Molecular Mass
² Avogardro constance
² Mole (as a unit)
² Atomic mole
² Molecular mole
² Molecular mass
4'0 Nature of Instruments ( Presentation of literature survey
5'0 Objectives ( 1' Skill development as a finder of
new knowledge
2' To enhance the skills of reporting observations
as a scientist.
3 'To involve in analyzing the reported information
using various criteria.
6'0 Instructions for implementation (
For teacher ( ² This is valid for second term science syllabus
in competency level in 1.1, 1.2, 1.3 and 1.4
Inform students to litriture survey start of the
second term.
² In this tool each student is involve in an individual
process.
² Direct the students subject content or part of
it to each student as your wish.

117

² Inform the students in advance the date at which
they have to submit the completed litreture
survey.
² Provide constructive suggestions once or twice
by examine their litreture survey before submition

For students ( ² Use litreture review for exploration for
activities nos. 1.1, 1.2, 1.3, 1.4 relevent to
second term in your science syllabus.
² Select to find information relevent to this topic
• Magazine

• News papers
• CD s
• Internet
² Be prepair to present information you have
collected by utilizing available resources.
² Mention the sources which you get the
information finelly in the litreture reveiw.
² Submitt your litreture review to your teacher on
due date.

7.0 Format for assessment and evaluation
:
Name of the student
Criteria

1. Keep information accurately
2. Accuracey of information
3. Report reference sources accurately
4. Follows instructions
5. Prsents the litreture review attractively

Indicate Proficiency Levels as A,B,C or D

A - Excellent
B - Good
C - Average
D - Should Improve

118


1.0 Evaluation : Term 2, Instrument 2

2.0 Competency levels covered : 3.7 and 3.8

3.0 Subject content covered : • Action of furance
• Fire extingusher and usage
4.0 Nature of Instrument : Preparation of information leaflet

5.0 Objectives : 1. Awearness of using combustion productivity at
day to day life.
2. To improve communication skills through informa

tion leaflet.

6.0 Instrutions for implementation :

For teachers • Encourage students to make a information leaflet.
relevent to " Action of furance and productivity
usage"or "fire extinguishers and accurate usage "
• Inform student about the source of information.
• Get student to refer the inforation leaflet issued by
various institutions.

For students • Prepair a information leaflet for public reguarding
" Action of furance and productivity usage" or "fire
extinguishers and accurate usage"
• Mark information which you have been collected
in infirmation leaflet concise, simple and atractive.
• Submit a prepaired infomation leaflet to your teacher
on due date.

119

7.0 Format for assessment and evaluation :

Names of Students

Criteria

• Relevance of information

• Presentation skills

• Creativity

• Reliability of information

• Completeness of information

Indicate Proficiency Levels as A,B,C or D

A - Excellent
B - Good
C - Average
D - Should Improve

120


1.0 Evaluation : Term 2, Instrument 3

2.0 Competency levels covered : 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.9, 3.10

3.0 Subject content covered : • Classification of chemical reaction
• Investigate interactions between matter and
electricity.
• Investigate reaction pattern of pure metals
• Examine the rate of the reaction of chemical reac
tions.

• Get the necessary action to prevent metal corrision.
• Preparation of gases and examine properties.
• Invetigate Heat changes relevent to chemical
reactions

4.0 Nature of Instrument : Chemistry practical workshop

5.0 Objectives : 1. To develope practical experiences relevant to
various chemical reactions.
2. To enhance maniuplations skills for setting experi-
mental appratus.
3. To direct the students on effective communication
through creations.

6.0 Instrutions for implementation :

For teachers • In this tool each student is involved in an individual
process as well as group process.
• Divide a class into seven groups and give the relevent
practical set.
• Provide the necessary facilities for practical test and
inform the students in advance the date at which they
have to conduct a workshop.
• Evaluate the students after the workshop.

For students • Present the practical test which is preplaned given by
teacher.
• Get the chance to present the relevent activity accu
rately
• Preplanned when the result of experiment is taken
several days.
• Plan the workshop when result of some experiment
is taken several days.

121

Chemistry

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