Question

In Ammonia molecule the bond angle is 107° and in water molecule it is 104°35', although in both the central atoms are sp³ hybridized Explain.

Answer 1

1. The ammonia molecule has sp³ hybridization. The expected bond angle is 109°28′. But the actual bond angle is 107°18′. It is due to the following reasons:
   1. One lone pair and three bond pairs are present in the ammonia molecule.
   2. The strength of lone pair-bond pair repulsion is much higher than that of bond pair-bond pair repulsion.
   3. Due to these repulsions, there is a small decrease in bond angle (∼2°) from 109°28′ to 107°18′.
2. The water molecule has sp³ hybridization. The expected bond angle is 109°28′. But the actual bond angle is 104°35′. It is due to the following reasons:
   1. Two lone pairs and two bond pairs are present in the water molecules.
   2. The decreasing order of the repulsion is Lone pair-Lone pair > Lone pair-Bond pair > Bond pair-Bond pair.
   3. Due to these repulsions, there is a small decrease in bond angle (∼5°) from 109°28′ to 104°35′.