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Iodine

What the name means: Iodine is named after the Greek word ioeides, meaning "violet coloured".

Iodine

Iodine atom

Iodine atom

 

 

 

Iodide ion

 

Iodide ion

 

Who identified iodine?: Bernard Courtois was a Frenchman who had been trained as a pharmacist. His father owned a factory that made saltpeter or niter. Saltpeter is a name given to potassium nitrate and sodium nitrate. There was a big demand for saltpeter at that time since it was an essential ingredient of gunpowder.

In order to make the saltpeter seaweed was collected from the Normandy and Brittany coastlines. This seaweed was then burned and the ashes were taken to the factory. Here they were treated with sulfuric acid as part of the process to obtain the saltpeter.

In 1811, Bernard Courtois made a mistake and added too much sulfuric acid to the ashes. The result was the production of a violet-coloured gas. Courtois collected some of this gas and, on cooling, it produced dark crystals. He was convinced that he had discovered something new but, since he didn't have enough money to continue his research, he passed samples of his crystals to various French chemists.

Charles Bernard Desomes and Nicolas Clement took up the research and presented their findings to the Institute of France in 1812. Louis-Joseph Gay-Lussac and Humphry Davy also received a sample from Courtois. Davy recognised that the new element had similar properties to chlorine and fluorine. He named the new element iodine.

After an argument about who had been the first to identify iodine, the chemists involved accepted that Bernard Courtois should take the credit.

 

Properties

IPROPS

STP = standard temperature and pressure.
Usually considered as room temperature and pressure.

 

About iodine: Iodine, in the form of iodide salts, is found in sea water and salt deposits. Iodine gas has a pungent odour and is purple-violet in colour. It dissolves in water to form a dark brown solution that is used as an antiseptic. Iodine is used to make some dyes and inks. It is an essential element for humans since it is needed for the thyroid gland in the neck to function properly.

 

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