how to find valency
Hi,
Valency is defined as the number of electrons gained or lost by an atom. The electrons present in the last shell determine the valency of a particular element. If,
· Number of valence electrons ≤ 4
Then the valency = number of valence electrons
· Number of valence electrons >4
Then the valency = 8 - number of valence electrons
If you consider the element‘magnesium’and write down its electronic configuration, it comes out to be 2, 8, 2. The electrons present in the outermost shell are 2 (which is less than 4), so the valency is equal to 2.
However, for element ‘oxygen’ the electronic configuration is 2, 6. The electrons present in the outermost shell are 6 (which is greater than 4), so the valency is equal to 8 – 6 = 2.
Hope it helps.
Cheers!