Iron(II) hydroxide
Iron(II) hydroxide or ferrous hydroxide is an inorganic compound with the formula Fe(OH). It is produced when iron(II) salts, from a compound such as iron(II) sulfate, are treated with hydroxide ions. Iron(II) hydroxide is a white solid, but even traces of oxygen impart a greenish tinge. The air-oxidized solid is sometimes known as "green rust".
Hydroxide
"Ortho"-periodic acid can lose all its protons, eventually forming the periodate ion [IO]. It can also be protonated in strongly acidic conditions to give the octahedral ion [I(OH)], completing the isoelectronic series, [E(OH)], E = Sn, Sb, Te, I; "z" = −2, −1, 0, +1. Other acids of iodine(VII) that contain hydroxide groups are known, in particular in salts such as the "meso"periodate ion that occurs in K[IO(OH)]·8HO.