Fomulas of Common Chemical Substances.pptx

Recognize the
formulas of
common chemical
substances
Competency

Specific
Objectives:
1. Identify the difference
between cation and
anion
2. Identify the names of
some simple binary
compounds
3. Recognize the

Cation
(+)
Cation
(+)
Anion
(+)
A neutral atom becomes an ion either by losing an electron
(cation) or by gaining an electron (anion)
Neutral
atom
loss of
electron(s)
gain of
electron(s)

Rules in Writing Formulas
1. Know the Symbols of Elements
Use the correct symbols for the elements from the
periodic table. For example, hydrogen is H,
oxygen is O, and sodium is Na.
2. Determine the Type of Compound
There are three main types of chemical
compounds:
Ionic Compounds: Made of metals and
nonmetals or polyatomic ions.
Covalent Compounds: Made of nonmetals

3. Writing Formulas for Ionic Compounds
Identify the cation (positive ion) and the anion
(negative ion). Write the cation first.
Balance the charges: The total positive and
negative charges must equal zero.
Use subscripts: Indicate the number of each ion
required to balance the charges. Do not write "1"
as a subscript.
Examples:
Sodium chloride: Na⁺ + Cl⁻ → NaCl
Magnesium chloride: Mg²⁺ + 2Cl⁻ → MgCl₂

4. Writing Formulas for Covalent
Compounds
Use prefixes to indicate the number of
atoms for each element.
Mono- (1), Di- (2), Tri- (3), Tetra- (4), Penta-
(5), etc.
The less electronegative element is
written first, followed by the more
electronegative element.
Examples:

5. Writing Formulas for Acids
Binary acids: Contain hydrogen and one
other element. Use the prefix "hydro-" and
the suffix "-ic acid."
Example: HCl Hydrochloric acid
→
Oxyacids: Contain hydrogen, oxygen, and
another element. Use the polyatomic ion's
name:
"-ate" becomes "-ic acid."
"-ite" becomes "-ous acid."

6. Use Parentheses for
Polyatomic Ions
If more than one polyatomic ion
is required, enclose it in
parentheses and add a subscript.
Example: Calcium nitrate: Ca²⁺ +
2(NO₃⁻) → Ca(NO₃)₂

1. Rules in monoatomic ions
a.For Cations
- the name of the element is unchanged.
- if an element can form two ions of different
charges, the name, which is usually derived
from its Latin name, is modified by the
suffix -ic for the ion with the higher charge,
and –ous for that with the lower charge.
b. For Anions
- the name of the element is modified by the
suffix –ide.

1. Name the following monoatomic cations:
a.Zn²⁺
b.Mg²⁺
c. K⁺
d.Fe²⁺
e.Fe³⁺
Answers:
f. Zinc ion
g.Magnesium ion
h.Potassium ion
i. Ferrous ion
j. Ferric ion

2. Name the following monoatomic
anions:
a.Brˉ
b.S²ˉ
c.O²ˉ
d.Iˉ
Answers:
e.Bromide ion
f.Sulfide ion
g.Oxide ion
h.Iodide ion

Rules in naming polyatomic ion (ionic
binary compound)
a.The name of a compound with two elements
has two words.
b.To get the first word, we use the name of the
first element or the element to the left of the
formula.
c.To get the second word, we use the name of the
second element and change the suffix to “ide” at
the end of the word.
Example: NaCl is sodium chloride

Name the following polyatomic ion:
a. NaI
b. KCl
c. BeS
Answers:
a.Sodium iodide
b.Potassium chloride
c.Berrylium sulfide

3. Rules in naming polyatomic ion ( ionic binary
compounds containing a metal ion with a variable
charge)
a. Compounds of these metals with nonmetals are named
with the same method as compounds in the first category,
except the charge of the metal ion is specified by a Roman
numeral in parenthesis after the name of the metal.
b. The charge of the metal ion is determined from the
formula of the compound and the charge of the anion.
Example: binary ionic compounds of iron and chlorine, iron
typically exhibits a charge of either 2⁺ or 3⁺
FeClշ is named iron (II) chloride
FeCl is named iron(III) chloride
ꝫ

Try naming the following ionic binary
compounds
a. CuCl
b. CuClշ
c. PbIշ
d. PbI4
Answers:
a. Copper (I) chloride
b. Copper (II) chloride
c. Lead (II) iodide

Steps to Determine the Roman Numeral:
1.Identify the charge of the anion or polyatomic
ion:
Look up the charge of the nonmetal or
polyatomic ion in the compound. Common
examples include:
1.Chloride (Clˉ) : -1
2.Sulfate (SO4²): -2
3.Nitrate (NO3ˉ): -1
2.Multiply the charge of the anion by its
subscript:

Set up an equation for the overall
neutrality:
The total positive charge contributed by
the metal cation must balance the total
negative charge contributed by the
anion(s).
1.Solve for the charge on the metal
cation:
Divide the total positive charge by the

Example 1: FeCl3(Iron(III) Chloride)
•Chloride ion charge: Clˉ (charge = -
1)
•There are 3 chloride ions, so the
total negative charge = 1×3= 3.
− −
•The compound must be neutral, so
the iron cation must have a total
charge of +3.

Example 2: Cu(NO3
)2 (Copper(II)
Nitrate)
•Nitrate ion charge: NO ˉ
ꝫ (charge = -
1)
•There are 2 nitrate ions, so the total
negative charge = 1×2= 2.
− −
•The compound must be neutral, so
the copper cation must have a total

Example 3: Crշ(SO4)3(Chromium(III)
Sulfate)
•Sulfate ion charge: SO4²ˉ(charge = -2)
•There are 3 sulfate ions, so the total
negative charge = 2×3= 6.
− −
•The compound must be neutral, so the
total positive charge contributed by
chromium = +6.
•There are 2 chromium ions, so each

Importance of Chemistry Formulas
Chemical formula in chemistry is like a
shorthand used to represent the elements
in a compound. The Periodic Table has
elements along with the symbols.
Hence, to know the nature of these
chemical compounds and their reactions,
chemistry formulas play a vital role. It gives
an idea of how a substance has formed and
the proportion of elements involved in that

Hence, to know the nature of
these chemical compounds
and their reactions, chemistry
formulas play a vital role. It
gives an idea of how a
substance has formed and the
proportion of elements

Fomulas of Common Chemical Substances.pptx

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Fomulas of Common Chemical Substances.pptx