Iodine, non-metallic element, element symbol I, periodic table element 53, in the fifth period of the periodic table, group 7, one of the halogen elements.
Elemental iodine was first discovered in 1811 by the French apothecary Koutwah. Elemental iodine is purplish black crystal, easy to sublimate, sublimate easy to condense, toxic and corrosive. Elemental iodine turns bluish-purple when it meets starch.
Mainly used in the manufacture of drugs, dyes, iodine, test paper and iodine compounds.