How is NH4+ ion formed? Formation of Ammonium ion: When ammonia (NH3) combines with H+ ion ,results in the formation of Ammonium ion through coordinate covalent bond. In ammonia ,Nitrogen is a central atom having 5 electrons in its valence shell ,3 electrons are shared with 3-H atoms and 1 lone pair of electron completeFormation of Ammonium ion (NH4+) -Coordinate Covalent Bond #ChemicalBonding – Digital Kemistry