Describe the hybridization in the case of PCl5 ? Why are the axial bonds longer compared to the equatorial bonds?
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Solution
Hybridization:
Hybridization is the process in which the atomic orbitals of comparable energies are mixed together.
This intermixing usually results in the formation of hybrid orbitals having entirely different energies, shapes, etc.
Features of Hybridization:
Atomic orbitals with equal energies undergo hybridization.
The number of hybrid orbitals formed is equal to the number of atomic orbitals mixed.
It is not necessary that all the half-filled orbitals must participate in hybridization. Even completely filled orbitals with slightly different energies can also participate.
Hybridization happens only during the bond formation and not in an isolated gaseous atom.
The shape of the molecule can be predicted if the hybridization of the molecule is known.
Types of Hybridization: Based on the types of orbitals involved in mixing, the hybridization can be classified as sp3, sp2, sp, sp3d, sp3d2, sp3d3.
Hybridization in the PCl5 molecule:
The atomic number of phosphorus is 15.
The electronic configuration of phosphorus is:
P=1s2 2s2 2p6 3s23p3
The hybridization in PCl5 is sp3d.
Therefore, the geometry of PCl5 is trigonal bipyramidal.
Axial bonds are longer as compared to equatorial bonds:
There are two types of bonds in PCl5, and they are axial and equatorial bonds.
The bond length of the axial bond is longer than the equatorial bond because the axial bond experiences more repulsion than the equatorial bond.
This makes the axial bond relatively weaker than the equatorial bond.
Hence, the axial bonds are longer than the equatorial bonds.
