Here's why:

* Valence Electrons: Nitrogen has 5 valence electrons (electrons in its outermost shell).

* Octet Rule: Atoms tend to gain, lose, or share electrons to achieve a stable octet (8 electrons) in their outer shell.

* Bonding: To achieve an octet, nitrogen needs to gain three more electrons. It can do this by forming three covalent bonds, sharing one electron from each bond with another atom.

Examples:

* Ammonia (NH3): Nitrogen forms three single bonds with three hydrogen atoms.

* Nitric Oxide (NO): Nitrogen forms a double bond with oxygen. One of the bonds is a coordinate covalent bond, where nitrogen donates both electrons to form the bond.

While nitrogen typically forms three bonds, it can sometimes form four bonds in special cases like ammonium ions (NH4+). However, this is less common.