Iodine was discovered in 1811 by Bernard Courtois when he was trying to extract potassium chloride from seaweed. By adding sulphuric acid a purple vapour was produced which formed into dark crystals. This was the element Iodine. Iodine’s name comes from the Greek word ‘Iodes’ meaning purple. Iodine easily forms compounds with group 1 and 2 elements usually uncoloured compounds and is one of the least reactive Halogens. Iodine is used in medicine, it is used as a disinfectant in surgery and also in the treatment of the thyroid. Silver iodide is used widely in photography and potassium iodide to clean wounds. In nature Iodine occurs mainly in seawater and seaweed a big source of Iodine for commercial use. It is located in Group 17 as a non metallic solid. It has a melting point of 113°c and a boiling point of 184°c.