Question

process of finding valacny

Answer 1

Valency is the combining and loosing capacity of electron of an element.
For a metal, it is their loosing capacity and for a non-metal, it is their combining capacity.
For example:- Na has 1 valance electron, so valency =1
Cl has 7 valence electron, so valency = 8-7 = 1

Process to find valency
For element having valence electron less than equal to 4
valency = valence electron

For element having valence electron more than 4(non-metals)
valency = 8- valence electron

Answer 2

It's very easy and simple. 
1st pt. No. of electrons in last shell should be 8 
2Nd Use 2n*n where n is the no. of the shell K,L,M etc. this formula is used to find no. of electrons that can be accommodated in a shell 
For ex if you want valency of element with atomic no.34 
Then Using the formula 
For 1st shell 2*1*1=2 
For 2nd shell 2*2*2=8 
For 3rd shell 2*3*3=18 
Here's the trick adding the electrons in these shells.=28 And the no. left is 6 
So as we know we need 8 electrons in last shell so, 2 electrons are less so the valency is -2 
If the atomic no.were 36 it would be a noble gas valency=0, 37 then a valency =+1

Hope this helps:)