An oxonium ion is any ion with a trivalent oxygen cation. It is the salt derived from the ammonium cation and the hydrosulfide anion. These charged groups are referred to as exchangers like cation and anion exchangers. Sodium is usually the first ion to break through a depleted cation exchanger. It is a salt composed of the sodium cation and the azanide anion. Hydrogen bonds link the cation and anions. Ammonium nitrate is a chemical compound, the nitrate salt of the ammonium cation. It is a salt composed of a sodium cation (Na) and a bicarbonate anion (HCO). Mercury occurs as a mercury(I) cation (Hg), formally a dimeric ion. It is an ionic compound consisting of two anions of gluconate for each zinc(II) cation. It is a zwitterion, consisting of both a quaternary ammonium cation and a carboxylate. Metallointercalators are complexes of a metal cation with polycyclic aromatic ligands. It is a salt of a diazonium cation and chloride. Many double salts containing nickel with another cation are known. Additionally, salts of the [RnF] cation with the anions , , and are known.