Question

Among the hydrides of group 15, predict the hydride having largest bond angle.

Answer 1

1. Among group 15 hydrides (NH₃, PH₃, AsH₃, SbH₃, BiH₃), NH₃ has the largest bond angle.
2. NH₃’s H-N-H bond angle is 107.8°, which is larger than the others due to nitrogen’s small size and high electronegativity.
3. This causes maximum repulsion between the lone pair and bond pairs, increasing the bond angle.
4. As the central atom size increases down the group, bond angles decrease (PH₃: 93.6°, BiH₃: 90°).
5. Hence, NH₃ has the largest bond angle due to stronger electron pair repulsion from its small and electronegative central atom.