Explain `sp^(3)d` hybridization `PCl_(5)` molecule.

Explanation

A molecule of phosphorus pentachloride has one phosphorus atom 5 chlorine atoms. Phosphorous atom has five electrons in the velence shell and chlorine atom has one electron to share.
P (ground state) : `[Ne] 3s_(2) 3p_(3)`
P (excited state) : `[Ne] 3s^(1) 3p_(x)^(1),3p_(y)^(1), 3p_(x)^(1), 3d^(1)`

During the formation `PCl_(3), 3s` three one 3d orbitals mix to form `sp^(3)` d hbrid orbitals. The `sp^(3)d` hybrid orbitals are towares five corners of trigonal bipyramid. Three covalent bonds are formed on one plane at an angle of `120^(@)`. Two more covalent bonds are formed at right angles to the palne. These are axial bons. The exail bonds are weaker than equatorial bonds because axial electrons suffer more repulsion from quatorial electrons. Hence `PCl_(5)` is more reactive Axial P-Cl bond length is 219 pm and equatorial P-Cl bond lenth is 204 pm.