Question

how is valency of element nitrogen or oxygen calculated

Answer 1

valency is the no.of electron share loose or gain by an atom.so as oxygen atomic no.is 8 it's configuration is 2,6 and so it needs two electron to complete configuration.so it's valency is 2-.in same manner nitrogens valency is 3-

Answer 2

Heya !!!

This is your answer....

To calculate the valency of any element, we have to see the last shell or valence shell.
If the number of atoms in valence is less than 4 then the valency of the element will be equal to number of valence electrons.

But, If the number of atoms in valence shell is more than 4. then the number of valence elctrons are subtracted from 8... and the result is the valency of the element.

In case of Oxygen.
The number of atoms in oxygen is 8.
Hence its electronics configuration is 2, 6.

So.... In valence shell. There are 6 electrons and hence valency = 8-6= 2.

In case of nitrogen...

Electronic configuration of nitrogen is ..
2, 5.

Hence. in valence shell there are 5 electrons which are more than 8.

So.. valency of nitrogen = 8-5 =3.

Hope it helps...