Periodic table

Periodic
Table
Elements are classified as metals, non metals
according to their valency.
Doberreiner gave law of triads(group of three elements)
Systematic study of elements and the large number of
compounds led scientists to develop some scientific
methods to classify the elements according to their
properties
Newlands represents law of octaves which means
elements are arranged in order of their
Increasing atomic weight, their properties repeated after
seven elements just like the nodes in music.
Lother-Meyer1869 plotted a graph between atomic
volume of different elements against their atomic mass
and found that similar elements occupy similar position on
the curve

 In 1869 Mendeleev`s put forwards the periodic law on
the basis of
Modern classification of element in the form of table know
as Mendeleev`s
Periodic table.
 He concluded that the physical and chemical properties
of the elements
Are periodic function of their atomic mass.
Mendeleev`s periodic table

Charecteristics of Mendeleev`s periodic
table
There are nine verticle column know as
groups
The group are numbered as I,II,III…..VIII
and zero.
Zero group consist inert gas element.
Each group from I to VII is further divided
into sub groups A and B.
Group VIII contain three sets with three
elements in each set.
GROUP

PERIOD
There are seven horizontal rows known as period.
Period are numbered from 1 to 7
The 1st period consist 2 elements
The 2nd and 3rd period consist 8 elements called as short
period.
The 4th and 5th period consist 18 elements each and called
as
Long period
The 6th period consist 32 elements called as longest
period.
The 7th period is incomplete and contain only 19 elements.

Periodic table

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