what is valency of an atom?

Hi Ananth,

The valency is defined as the number of electrons gain or lost by an atom.

The electrons present in the last shell determine the valency of a particular element.

If,

If you consider the element ‘aluminium’ and try to write its electronic configuration, then it is 2, 8, 3 the valency is equal to 3.

However, for element ‘oxygen’ having electronic configuration 2, 6 the valency is 8 – 6 = 2.

 

Hope it is clear to you.

Cheers!