Question

how to find valency of a element?examples.

Answer 1

I will explain this by an example of "carbon" as we know that the Valency of carbon is 4. But how it is found!
following steps have to done to find the valency of carbon or any other atom.
1-)Atomic number of atom. (As we know that atomic number of carbon is 6).
2-)In Kshell we filled 2 electrons. (Carbon has 6 elections filled two in K shell).
3-)Now the turn of L shell in this she'll we can fill maximum 8 electron. (In carbon there is remaining only 4 electron so we filled these electron in it).
So, the last shell that is L shell in carbon will be the Balence of it that is 4.

Answer 2

first we have to take the atomic number of the element we want to find valency
lets take an example like

Calcium
atomic number = 20

now we have to find a noble gas (element) whose atomic number is nearest to the atomic number of the element
atomic number of Calcium i.e, 20 is nearest to Argon
whose atomic number is 18

Now , to find valency

atomic number of the choosen element -
atomic number of nearest noble gas

atomic number of Calcium - Atomic number of Argon
20 - 18 = 2

so the valency is 2

So this is the way to find valency of any element





Hope this helps you