Question

Define valency by taking examples of nitrogen and boron.

Answer 1

Valency is the tendency of any atom to from ion by gaining or losing certain number of electrons. It is the number of outermost electrons in the outermost orbit.

Nitrogen has electronic configuration 2,5. So, that it needs 3 more electron to complete its last orbit. Boron has electronic configuration 2,3. So it will lose 3 electrons rather than gaining 5 electrons. Thus the valency of nitrogen and boron is 3.