Question

Is there any change in the hybridisation of B and N atoms as a result of the following reaction? 
\(BF_3+ NH_3 \rightarrow F_3B.NH_3\)

Answer 1

Given reaction:

BF₃ + NH₃ → F₃B·NH₃

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Hybridisation before reaction:

• In BF₃, the boron atom is sp² hybridised.
It has three sp² hybrid orbitals forming three B–F σ bonds and one vacant p-orbital.

• In NH₃, the nitrogen atom is sp³ hybridised.
It forms three N–H σ bonds and has one lone pair of electrons.

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Hybridisation after reaction:

In the product F₃B·NH₃, the lone pair of electrons on nitrogen is donated to the vacant p-orbital of boron, forming a coordinate (dative) bond.

• After accepting the lone pair, the boron atom now forms four σ bonds.
Hence, the hybridisation of boron changes from sp² to sp³.

• The nitrogen atom continues to use four sp³ hybrid orbitals (three N–H bonds and one coordinate bond).
Therefore, the hybridisation of nitrogen remains sp³.

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Final Conclusion:

• Hybridisation of boron: changes from sp² to sp³
• Hybridisation of nitrogen: no change (remains sp³)