Iodine

Iodine is one of the more well known chemicals on the periodic table. This chemical is the heaviest of the stable halogens and exists as a purple/black metallic solid when it is at standard conditions. It was originally discovered in 1811 and has a wide variety of different applications. For example, about half of all iodine is used to produce an assortment of organoiodine compounds. It is also used in animal feed supplements, sanitation, photography, and pharmaceuticals.