Although geometries of `NH_(3)` and `H_(2)O` molecules are distorted tetrahedral, bond angle in water is less than that of ammonia. Discuss.

Explanation

In `overset(* *)NH_(3)and "in" H_(2)overset(* *)(O":")` molecules the central atom is surrounded by four electron pairs. The geometries of these molecules are expected to be tetrahedral. They however, get distorted on account of the presence f lone electron pairs. On comparisionk, the bond angle in `NH_(3)(107^(@))` is more than in `H_(2)O(104^(@)).` This is on occount of greater magnitude off form of lone pair : lone repulsion in `H_(2)O` molecule as compared to lone pair : shared pair repulsion in `NH_(3)` molecule. For more details, consult section 4.14.