Question

pcl5 in known but ncl5 is not why

Answer 1

in N there is no vacant d-orbital so N can not accommodate 5 Cl at a time. in the other hand having d-orbital P can accommodate 5Cl at a time.

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.