Density
4.93 g/cm³ (at 20 °C)
Discovery
Iodine was discovered in 1811 by Bernard Courtois, a French chemist and saltpeter manufacturer.
Common Uses
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Used in antiseptics and disinfectants, such as tincture of iodine and iodophors.
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Silver iodide is used in photography.
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Potassium iodide is used as a dietary supplement and to protect the thyroid gland from radioactive iodine.
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Used in some types of lighting, such as halogen lamps.
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Used as a catalyst in some chemical reactions.
Interesting Facts
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Iodine is a purplish-black nonmetallic solid at room temperature that sublimes (turns directly into a gas) to form a violet gas with a pungent odor.
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Starch turns a deep blue-black color in the presence of iodine, which is a common test for the presence of starch.
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The name "iodine" comes from the Greek word "iodes," meaning "violet-colored."
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Iodine is essential for the production of thyroid hormones, which regulate metabolism.
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