Question

Describe the shapes of BF₃and BH^-₄ ? Assign the hybridization of boron in these species?

Answer 1

Hybridization:

• Hybridization is the process in which the atomic orbitals of comparable energies are mixed.
• This intermixing usually results in the formation of hybrid orbitals having entirely different energies, shapes, etc.
• The atomic orbitals of the same energy level mainly take part in hybridization.

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.

BF₃ molecule is formed by bonding between three sp² orbitals of B (Boron) and 3p orbitals of 3 F (Fluorine) atoms. The halides of the boron form trigonal planar geometry.

The central atom B (boron) in BH4⁻​ undergoes sp³ hybridization which results in tetrahedral geometry with 4 bond pairs and 0 lone pairs of electrons.