Origin : The name is derived from the Greek 'iodes', meaning violet
1811-Iodine comes as black, shiny crystals that dissolve in alcohol; the result is sold as an antiseptic solution. Iodine salts (iodides) are used in dyes and photography, as industrial catalysts and in the manufacture of pharmaceuticals. Iodine is also an essential element for humans, who require a daily intake of iodine (as iodide) of about a tenth of a milligramme (only 1/300,000th of an ounce). Our bodies contain up to 20 milligrammes, mainly in the thyroid gland. Normally we get enough from the food we eat, but people eating food grown in areas where the soil lacks iodides can develop a swoll
(ii) Around 21% is used to produce potassium iodide and 10% of the iodine is used as sodium iodide. Most of the rest is made into a variety of organic compounds. Silver iodide is used in photographic chemicals.
(iv) The world production of iodine is relatively small (under 10,000 tonnes per year), with the bulk coming from Chile, USA, Japan and Russia.
Bernard Courtois observes clouds of purple vapour rising from mother liquor of seaweed ash acidified with sulphuric acid (used as a source of sodium and potassium salts). The vapours condensed on cold surfaces to yield dark crystals with a metallic luster
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