Question

Why does bond angle decreases in hydrides of nitrogen family while going down a group?

Answer 1

As we move down the group the central atom is less hybridized due to Inert pair effect and is closer to pure p-character. This is because, as we go down the group due to increase in energy gas between s and p orbital as value of n increase, he s orbital becomes reluctant in hybridisation and pure p orbitals are involved in bonding. Thus, bond angle decreases down the group.