Solutions containing the hydroxide ion attack glass. Hydrochloric acid is the salt of hydronium ion, HO and chloride. A bromide is a chemical compound containing a bromide ion or ligand. It is calibrated against buffer solutions of known hydrogen ion activity. Electrolytes enter and leave cells through proteins in the cell membrane called ion channels. The number of water molecules attached to each metal ion is constant. Such anisotropy is maximized in deep reactive ion etching. This is known as the chemical part of reactive ion etching. Magnesium occurs typically as the Mg ion. The simplest is the helium hydride molecular ion, HeH, discovered in 1925. The nitrite ion, which has the chemical formula . Precursor ion scanning refers to monitoring for a specific loss from the precursor ion. The coordination sphere of the zinc ion is approximately tetrahedral. Metalloproteins are a group of proteins with metal ion cofactors. There are two ways of looking at an equilibrium involving hydrolysis of an aqua ion.