Question

Why bond angle of ammonia is greater than phosphine?

Answer 1

Bond angle of NH3 is greater than PH3

Bond angle is directly proportional to EN of central meta atom

En of these two are as follows

N=3
P=2.1

so by comparison EN of N is greater hence Bond angle of NH3 is greater than PH3

Answer 2

Bond angle of Ammonia(NH3) is more Phosphine(PH30 because -

-The Nitrogen (N) atom is more electronegative than Phosphorous (P)

- So the electron pair is more tightly held.

- Whereas this electron pair is drifted apart n Phosphine because of decreased electronegativity of P.

- Also the repulsion between a lone pair and bond pair is always the strongest, this also leads to more repulsion and increased bond angle in Ammonia