Question

The bond angle in ammonia is 107°48¹ instead of 109°28¹. Explain the reason.​

Answer 1

Answer:

Nitrogen in Ammonia has sp3 hybridization. So , it's natural to think that the compound will be present in Tetrahedral form.

It is expected that the bond angle will be

109°28'

But, in reality, the bond angle is smaller than the expected angle.

The main reason for this:

1. Presence of Lone pair - Bond pair repulsion.

2. Presence of Bond pair - Bond pair repulsion.

This pushes the bonds towards each other and hence the bond angle decreases to 108°48'

Diagram:

Please refer to the attached file to understand better.

Answer 2

$\huge{\orange{\underline{\red{\mathtt{CORRECT \: QUESTION :-}}}}}$

The bond angle in ammonia is 107°48' instead of 109°28'. Explain the reason.

$\huge{\orange{\underline{\red{\mathtt{EXPLANATION :-}}}}}$

The organisation of electron pairs are ruled by the VSEPR (Valence Shell Electron Pair Repulsion) . In a structure of 3 pairs of electrons like BF3 it is 120°because the maximum distantance between the electrons pair are a flat triangular structure so 360°/3 →120°

Because Nitrogen has a free electron pair, it corresponds to a 3 dimensional structure close to the tetrahedron:

It should be 109.5° (Perfect tetrahedron) but the non bonding pair of electron occupy more space so it is 107°.

$\huge{\orange{\underline{\red{\mathtt{THANKS.</p><p>}}}}}$