Question

the group, the element Ar is bigger in size.
Explain the variation in the following properties of the elements in the periodic table.
(a) Atomic radius in the periodic table (b) Metallic character in a period (c) Valency in a group.
(C.B.S.E. Sample Paper 2
(a) For answer, consult section 5.5.
(6) For answer, consult section 5.5.
(c) For answer, consult section 5.5.​

Answer 1

There are 7 periods in the modern periodic table.

Metallic character tends to decrease on going across a period whereas the number of valence electrons increases in a period and valency first increases from 1 to 4 and then decreases from 4 to 0.

Atomic radius increases from top to bottom within a group. This is caused by the addition of a new shell. In a group, the number of valence electrons does not change. Hence, all the elements of one group have the same valency.