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Bernard Courtois, VIIa, atomic number, stunted growth, periodic table

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>  Properties and Occurence

Iodine, symbol I, chemically reactive element, a blue-black solid at room temperature. In group 17 (or VIIa) of the periodic table, iodine is one of the halogens. Its atomic number is 53.

Iodine was first isolated from seaweed residues in 1811 by Bernard Courtois, a French manufacturer of saltpeter. The discovery was confirmed and announced by the French chemists Charles Desormes and Nicholas Clement. The nature of the element was further established in 1813 by the French chemist Joseph Louis Gay-Lussac, who also gave iodine its name.


Iodine is medicinally very important because it is an essential trace element, present in a hormone of the thyroid gland that is involved in growth-controlling and other metabolic functions. Without iodine, stunted growth and conditions such as goiter can result. Thus in areas where iodine is not sufficiently abundant naturally, iodine-containing salt serves to make up the deficit. In medicine, iodine-alcohol solutions and iodine complexes have been used as antiseptics and disinfectants. Radioisotopes of iodine are used in medical and other fields of research. More broadly, various iodine compounds find use in photography, the making of dyes, and cloud-seeding operations. In chemistry, various iodine compounds serve as strong oxidizing agents, among other uses.

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Bernard Courtois, VIIa, atomic number, stunted growth, periodic table, goiter, strong oxidizing agents, antiseptics, Iodine, thyroid gland, deficit, hormone, room temperature, disinfectants, discovery, element, chemistry, symbol, medicine, nature, photography, areas, uses, group, conditions

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