In chemistry, NH4 is the chemical formula for ammonium. It is a positively charged ion, known as a cation, with a charge of +1. NH4 contains one atom of nitrogen, represented by N, and four atoms of hydrogen, represented by H.
An ammonium ion is formed by a reaction between ammonia, or NH3, and a hydron ion, which is a positively charged hydrogen atom symbolized as H+. A pair of electrons forms the bond between the ammonia molecule and the hydrogen ion.
Ammonium is often found in compound salts, such as ammonium chloride and ammonium carbonate. It has a molar mass of 18.03 grams per mole and an acidity level of 9.25.