Ammonia (${\mathrm{NH}}_3$)

Ammonia is $\mathrm{N}{\mathrm{H}}_3$, a pyramidal molecule with a nitrogen lone pair. The lone pair can accept a proton to form ammonium or coordinate a Lewis acid.

In water, the Ammonia-ammonium equilibrium affects pH. Molecular Ammonia and the ammonium ion therefore have different charge states and should not be treated as interchangeable species.^[ref]