Iodine.

Some Iodine crystals.

General Info.

Iodine is a blue/black crystalline solid discovered in 1811 in France by Bernard Courtois, who obtained it by pouring concentrated sulphuric acid onto seaweed ash. At room teperatures iodine dissolves into a violet vapour which irritates the eyes, nose and throat, and is therefore kept dissolved in alcohol or water.

Properties.

Iodine is the least reactive and heaviest of the halogens. It is expelled from molecules by the others and is readily absorbed by activated carbon.

Uses.

Iodine is the most useful halogen of them all. It is needed for the thyroid gland at the base of the brain, and a lack of it causes goitre and cretinitis. Only one tea spoon's worth of iodine is needed in a lifetime, but, in third world countries, there are still fairly wide spread cases of iodine-deficiency disorders.
As suprising as it seems, iodine is also used in certain lasers and photography, as well as being used in many dyes.
Without it, you may not be dead, but you certainly wouldn't be here.

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