The periodic table/Iodine

Discovery
Iodine was discovered by French chemist Bernard Courtois (1777-1838) in 1811. Charles Bernard Desormes, Nicolas Clément and Joseph Louis Gay-Lussac were given samples of Iodine to continue their research of Iodine. The discovery was made public by Desormes and Clément on November 29, 1813, as they scheduled a meeting for the substance in the Imperial Institute of France. Gay-Lussac awarded the element's name, iode, from the Greek Word (ιώδες) for violet (because of the color of iodine vapor).

On December 10, 1813, English chemist Humphry Davy (he was given a sample of Iodine) sent a letter to the Royal Society of London, stating that he had identified a new element. Immediately, Davy and Gay-Lussac erupted up in arguments on who discovered the element first, but both agreed on that Courtois was the first to isolate the element.

Iodine in the body
Iodine is an essential trace element; the thyroid hormones (thyroxine and triiodotyronine) contains iodine. According to the World Health Organization, in 2007, 2 billion individuals had insufficient iodine intake, 1/3 being of school age.

Quick Facts
Name: iodine atom

Symbol: I

Atomic Mass: 126.90447 amu

Classification: group 7 (halogens)

Protons: 53

Electrons: 53

Neutrons: 74

Color: black solid, purple vapour

Discovery in: 1811

Density: 4.933 g/cm3

Crystal Structure: orthorhombic

Melting Point: 113 °C (387 K)

Boiling Point: 184 °C (457 K)

Common Uses: germicides, antiseptics, dyes, table salt, photography