Question

Explain the formation of boron trifluoride on the basis of hybridization.

Answer 1

Formation of boron trifluoride on the basis of sp² hybridization :

i. Boron trifluoride (BF₃) has one boron atom and three fluorine atoms.

ii. Observed valency of boron in BF₃ molecule is three and its geometry is trigonal planar.

This can be explained on the basis of sp² hybridization.

iii. The ground state electronic configuration of B (Z = 5) is 1s² 2s² \(2p_x^1\) \(2p_y^0\) \(2p_z^0\).

Electronic configuration of boron :

iv. One electron from 2s orbital of boron atom is uncoupled and promoted to vacant 2p_y orbital.

v. The three orbitals i.e. 2s, 2p_x of and 2p_y of boron undergoes sp² hybridization to form three sp² hybrid orbitals of equivalent energy, which are oriented along the three comers of an equilateral triangle making an angle of 120°.

vi. Each sp² hybrid orbital of boron atom having unpaired electron overlaps axially with half-filled 2p_z orbital of fluorine atom containing electron with opposite spin to form three B-F sigma bonds by sp² -p type of overlap.

vii. Each F-B-F bond angle in BF₃ molecule is 120°. The geometry of BF₃ molecule is trigonal planar.

Diagram :