Describe shapes of BF₃ and BH₄^- . Assign hybridisation of boron in these species.

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p-Block Elements - I

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Describe the shapes of $BF_3$ and $BH_4^-$. Assign the hybridisation of boron in these species.

Option A

Option B

Option C

Option D

Solution

$(i)$ $\mathrm{BF}_{3}:$ As a result of its small size and high electro-negativity, boron tends to form monomeric covalent halides. These halides have a planar triangular geometry.

This triangular shape is formed by the overlap of three $s p^{2}$ hybridised orbitals of boron with the $s p$ orbitals of three halogen atoms. Boron is $s p^{2}$ hybridised in $\mathrm{BF}_{3}$.

$(ii)$ $\mathrm{BH}_{4}^{-}$: Boron-hydride ion $\left(\mathrm{BH}_{4}^{-}\right)$is formed by the $s p^{3}$ hybridisation of boron orbitals. Therefore, it is tetrahedral in structure.

Standard 11

Chemistry