Ammonium is a positively charged polyatomic ion made of nitrogen and hydrogen, commonly found in fertilizers and in compounds used in some household disinfectants.
Ammonium is composed of one nitrogen atom bonded to four hydrogen atoms, carrying a net positive charge. It forms when ammonia (a nitrogen atom bonded to three hydrogen atoms) accepts a hydrogen proton. Ammonium can bond with negatively charged ions to form salts. Some ammonium salts, such as ammonium nitrate, are used in fertilizers to provide nitrogen that helps plants grow. Certain other ammonium-containing compounds are used in cleaning products as disinfectants to kill germs and bacteria.