Ammonium

The ammonium (more obscurely: aminium) cation is a positively charged polyatomic cation with the chemical formula NH₄+. 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 (NR₄+), where one or more hydrogen atoms are replaced by organic radical groups (indicated by R).