The chemical and physical properties of elements are a
periodic function of their atomic numbers.
The periodic table based on modern periodic law is called
as Modern Periodic Table.
EXPLAINATION / POSITION OF ELEMENTS IN THE MODERN
PERIODIC TABLE:-
Horizontal rows in the table are called as periods.
Vertical column in the table are called as groups.
Table consists of seven periods and eighteen groups.
Periods are numbered from 1 to 7.
Elements are present in the same period have same number
of shells which is equal to the period number.
In each period a new shell starts filling up.
The first period is shortest period containing only 2 elements.
Second and third are called as short periods. They contain 8
elements each.
Fourth and fifth are long periods. They contain 18 elements
each.
Sixth period is the longest periods. It contains 32 elements.
Seventh period is incomplete period.
Groups are numbered from 1 to 18.
Elements having same number of valence electrons or having
same outer electronics configuration are present in the same
group.
Elements present in the same group show same chemical
properties.
Group1 contain alkali metals.
Group2 contains alkaline earth metals.
Group17 contains halogens.
Group18 contains inert gases.
Metals are present on the left hand side of the periodic table.
Non-metals are present on right hand side of the periodic
table.
Group 1 and group2 are on left side. Group13 to froup17 are
on right side of the periodic table. Such groups are called as
normal elements. Their one outermost is incomplete.
Group3 to group12 in the middle of the periodic table are
called as transition elements. Their two outermost is
incomplete.
Group18 is on right hand side which contains inert gases.
Their outermost shell contains eight electrons.
Bottom elements are called as inner transition elements.
Bottom elements contain two series of elements lanthanides
and actinides.
Elements are classified on the basis of their electronic
configuration.
Elements are divided into four blocks. S-block, p-block, dblock and f-block.
Group1 and group2 are included in s-block.
s-block elements are metals and contain 1 or 2 electrons.
Group 13 to group 17 and 0 group are included in p-block.
p-block elements are metals, non-metals and metalloids. And
contain 3 or 8 electrons.
s-block and p-block elements are called as normal elements.
Outermost shell incomplete except 0 group.
0 group elements have complete outermost shell. They are
called as inert or noble elements.
Group3 to group12 are included in d-block.
d-block elements are known as transition elements.
d-block elements are metals.
In the d-block Outermost shells incomplete.
MERITS OF MODERN PERIODIC TABLE OVER MENDELEEV’S PERIODIC
TABLE:-
All isotopes of the same elements have different masses but
same atomic number. Therefore they occupy the same
position in the modern periodic table.
When elements are arranged according to atomic numbers
the anomaly regarding certain pairs of elements in
Mendeleev’s periodic table disappears.
Elements are classified according to their electronic
configuration. Into different blocks.