Question

Describe the shapes of BF₃ and BH₄ ^– . Assign the hybridisation of boron in these species. Hybridisation of B in BH4​

Answer 1

(i) BF₃ 

As a result of its small size and high electronegativity, boron tends to form monomeric covalent halides. These halides have a planar triangular geometry. This triangular shape is formed by the overlap of three sp² hybridised orbitals of boron with the sp orbitals of three halogen atoms. Boron is sp² hybridised in BF₃. 

(ii) BH₄ ^– 

Boron-hydride ion (BH₄ ^– ) is formed by the sp3 hybridisation of boron orbitals. Therefore, it is tetrahedral in structure.