Question

PCl5 exists but Ncl5 does not why?

Answer 1

  PCl5 forms five bonds by using the d-orbitals to   expand the octet" and have more  places  to put bonding pairs of electrons. NCl5 does not exist because there are no d-orbitals in the second energy level. Therefore there is no way to arrange five pairs of bonding electrons around a nitrogen atom.

Answer 2

Pcl5 exist as
Electronic configuration of P(15): 1s2 2s2 2p6 3s2 3p3
After 3p 3d orbital comes so PCl 5 can exisit
But NCl5 does not exist because
Electronic configuration of N(7): 1s2 2s2 2p3
Now 2 energy level does not contain d orbital so NCl5 does not exist
Hybridization of PCl5 is sp3d
But N doest not have d orbital so cant have hybridization sp3d