The ammonium (more obscurely: aminium) cation is a positively charged polyatomic cation with the chemical formula NH+
4. It is formed by the protonation of ammonia (NH3). Ammonium is also a general name for positively charged or protonated substituted amines and quaternary ammonium cations (N+R4), where one or more hydrogen atoms are replaced by organic radical groups (indicated by R).
In the substitutive nomenclature NH4+ is denoted by the name azanium instead of ammonium.