Question

Explane with reason the variation of valency on going down in a group

Answer 1

The valency of an element neither increases nor decreases on growing down the group becuase the number of valence electrons remains same in a group.

Answer 2

when we move from left to right in periodic table valency increases.but after 4 is decreases also.The electrons present in the last shell determine the valency of the element.if the no. electrons <4:no.of the valence electrons.If the no. of element >4:8-no. of the valence electrons.