Dr Daniel J Bell et al.

Iodine (chemical symbol I) is one of the trace elements. Its biological importance is its central place in the physiology of the thyroid gland and, in radiology, as the key chemical constituent of most of the radiographic, fluoroscopic, and CT contrast media.


Basic chemistry

Iodine has the atomic number 53 with an atomic weight of 126.90 g/mol. It is a shiny purplish solid in the halogen group.

History and etymology

Elemental iodine was discovered in 1811 by Bernard Courtois, a French chemist, as a gas produced when seaweed was doused with sulfuric acid (during synthesis of nitre, a precursor to the manufacture of fertilisers and gunpowder). It was another two years before Louis Gay-Lussac and Sir Humphry Davy crystallized the gas as a purplish solid. They named it for its distinctive color, from the Ancient Greek word ιωδης, (iodes) meaning violet-colored 1.

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Article information

rID: 55910
System: Head & Neck
Section: Pathology
Tag: stub, refs
Synonyms or Alternate Spellings:
  • Iodine (I)

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