Question

why pcl5 exists and not ncl5

Answer 1

this is because phosphorus has a vacant 3d orbital where as nitogen does not have it .

phosphorus can expand its octate by hybridization.

Answer 2

Phosphorous has d-orbitals & hence

can accommodate the electrons

from Cl into them,in case of N the

d-orbitals are absent & electrons can be

accommodated only in p-orbitals.Hence

PC15 exists.