Question

what is valency? explain it?

Answer 1

hi

In chemistry, the valence or valency of an elementis a measure of its combining power with other atoms when it forms chemical compounds or molecules. The concept of valence developed in the second half of the 19th century and helped successfully explain the molecular structure of inorganic and organic compounds.

Answer 2

In chemistry, the valency of an atom is a measure of its combining power with other atoms when it forms chemical compounds or molecules.

ATOMIC NO OF NITROGEN IS 7 

K shell =2 
L shell  =5

it requires 3 more electrons to obtain its octet

so the valency of nitrogen is -3