Bond formation in ammonia molecule. Animation of the sharing of electrons (dots and crosses) between three hydrogen (H) and one nitrogen (N) atom to form a molecule of ammonia (NH3). This is an example of covalent bonding, with the three single bonds shown here formed by a shared electron pair consisting of an electron from each atom. The outer electron shell of each atom is shown as a blue ring. Ammonia is a gas at room temperature and pressure.