Here's why:

* Nitrogen (N) has 5 valence electrons and needs 3 more to complete its octet.

* Hydrogen (H) has 1 valence electron and needs 1 more to complete its duet.

To form a stable compound, they need to share electrons. However, with just one nitrogen and one hydrogen atom, there are not enough electrons to form a stable bond.

The most common and stable compound containing nitrogen and hydrogen is ammonia (NH₃). In ammonia, the nitrogen atom shares its electrons with three hydrogen atoms, forming three covalent bonds.