Question

How many hybrid orbitals are present in the molecule ${\mathrm{PCl}}_5$?

Answer 1

Hybridization:

• Hybridization is known as the concept of mixing two atomic orbitals of comparable energies to give rise to a new set of types of hybridized orbitals.
• This intermixing generally results in the formation of hybrid orbitals having entirely different energies, shapes, etc.
• Basically, these hybrid orbitals are quite useful in explaining atomic bonding properties and molecular geometry.

Hybrid orbitals for the molecule ${\mathrm{PCl}}_5$:

• Hybridization is known as the process of mixing atomic orbitals of similar energy to generate a new set of orbitals.
• In the case of the given molecule ${\mathrm{PCl}}_5$ ; the P atom requires five orbitals to form the five $\mathrm{P}-\mathrm{Cl}$ bonds.
• The outermost valence shell electronic configuration of P in the ground state is given as =$3{\mathrm{s}}^{2}3{\mathrm{p}}^3.$
• Here, the P atom has only one $3\mathrm{s}$ orbital and three $3\mathrm{p}$ orbitals, therefore it uses one of its 3d orbitals to form the fifth bond.
• Hence, the electronic configuration of P in the excited state is given as =$3{\mathrm{s}}^{1}3{\mathrm{p}}^{3}3{\mathrm{d}}^1$
• These five mentioned orbitals are hybridized to form five ${\mathrm{sp}}^3\mathrm{d}$ orbitals and form a trigonal bipyramid geometry given as;

• Here, 3 hybrid orbitals directed towards the corners of an equilateral triangle are called equatorial hybrid orbitals which are planar and have a bond angle of $120°$.
• Whereas the 2 hybrid orbitals which are perpendicular to the plane of the equatorial hybrid orbital are called axial hybrid orbitals and form a 90° angle with the equatorial hybrid orbitals.

Hence, hybrid orbitals are present in the molecule ${\mathrm{PCl}}_5$, are five ${\mathrm{sp}}^3\mathrm{d}$ orbitals that generate the trigonal bipyramid geometry.