Facts about Iodine
The radioactive isotopes iodine-123 and iodine-125 are used as probes for imaging the thyroid and evaluating its health.
Chemically, iodine forms compounds with many elements, but it is the least reactive of the halogens.
When mixed with ammonia, iodine can form nitrogen triiodide, which is extremely sensitive and can explode unexpectedly.
Iodine does not react with oxygen or nitrogen, but with ozone it forms an unstable oxide, I4O9.
The decay of 129I is the basis for the iodine-xenon radiometric dating scheme, which covers the first 50 million years of development of the solar system.
The U.S. Food and Drug Administration recommends an intake of 150 micrograms of iodine per day for both men and women.
The thyroid hormones thyroxine (T4) and triiodothyronine (T3) contain four and three atoms of iodine per molecule, respectively.
A list of notable inorganic compounds of iodine is given below, in alphabetical order.
A major argument erupted between Davy and Gay-Lussac over who identified iodine first, but both scientists acknowledged Courtois as the first to isolate the substance.
A number of organic compounds containing iodine are useful in the preparation of pharmaceuticals and dyes.
Under appropriate conditions, iodine reacts with other halogens—fluorine, chlorine, and bromine—to produce "interhalogen" compounds, including IF3, IF5, IF7, ICl, I2Cl6, and BrI.
The name iodine was coined from the Greek word iodes, meaning "violet."
Iodine was discovered in 1811 by the Frenchman Bernard Courtois, when he was working with his father to manufacture saltpeter (potassium nitrate).
The thyroid actively absorbs elemental iodine from the blood to make and release these hormones into the blood, actions that are regulated by a second hormone (thyroid-stimulating hormone, TSH) from the pituitary.
Iodine (chemical symbol I, atomic number 53) is a nonmetal that belongs to a group of chemical elements known as halogens.
The most common compounds of iodine are the iodides of sodium and potassium (NaI, KI) and the iodates (NaIO3, KIO3).
Iodine occurs in nature in the form of iodide ions, chiefly in solution in seawater but also in some minerals and soils.
Iodine reduces thyroid hormone and can kill fungus, bacteria, and other microorganisms such as amoebas. A specific kind of iodine called potassium iodide is also used to treat (but not prevent) the effects of a radioactive accident.