Question

How do we calculate the valency of an element from its electronic configuration?
-Haw does the valency vary in a period?
-How does the valency vary in going down a group?​

Answer 1

Answer:

We find valency of an element from its electronic configuration by subtracting its valence electron from 8.

Valency In a period goes on increasing.

valency in going down a group remain same.

Answer 2

Explanation:

1) The valency of any element depends on the numbers of valence electrons i.e. the number of electrons present in the outermost shell. The number of electrons lost or gained to obtain the electronic stability of nearest noble gas is the valency of that element(octet or duplet rule) . e.g. calcium has electronic configuration 2,8,8,2 i.e. it will have 2 electrons in the outermost shell. it needs to loose 2 electrons to gain the stability of the nearest noble gas argon. Hence, it's valency is 2.

I am not sure how to explain the rest 2 but hope this helps :)