The ammonium ion, represented as NH4+, is a positively charged polyatomic ion formed when ammonia (NH3) accepts a proton (H+). It consists of one nitrogen atom bonded to four hydrogen atoms. Ammonium is commonly found in nature, particularly in soil and water, where it plays a crucial role in the nitrogen cycle. Ammonium ions are important in various biological and chemical processes. They are utilized by plants as a nitrogen source for growth and are also present in fertilizers. Additionally, ammonium ions can be involved in the formation of salts, such as ammonium chloride (NH4Cl), which have various industrial applications.