Question

How valency of elements changes:-
(i) Along the period from left to right
(ii) Down the group from top the bottom

Answer 1

(a) Valency remains same on moving from top to bottom in a particular group. This is because the outermost electronic configuration of all the elements in a group remains same.

(b) On moving from left to right in a period, the number of valence electrons in elements increases from 1 to 8. The elements in a period have consecutive atomic numbers.

On moving down a group in the periodic table, the number of valence electrons in the elements remains the same.

Answer 2

Valency

Explanation:

Valency of an element is a measure of its combining power with other atoms when it forms chemical compounds or molecules.

(i) As we move from top to bottom in a periodic table, there is no change in valency. This is because the outermost electronic configuration of all the elements in a group remains the same.

(ii) As we move from left to right in a periodic table, the number of valence electrons in elements increases from 1 to 8. The elements in a period have consecutive atomic numbers.