Here's why:

* Nitrogen's Valence Electrons: Nitrogen has 5 valence electrons.

* Hydrogen Bonding: Each hydrogen atom contributes 1 electron for bonding.

* Total Electrons: In NH₃, there are a total of 8 electrons (5 from nitrogen + 3 from hydrogen).

* Bonding: These 8 electrons are used to form 3 single bonds between nitrogen and each hydrogen atom.

* Lone Pair: This leaves 2 electrons remaining on nitrogen, which form a lone pair.