Who invented iodine and when?

Answer 1

Nobody 'invented' iodine ,it was discovered. In 1811 Bernard Courtois accidentally discovered iodine. The discovery was announced in 1913.He used to extract saltpetre from seaweed, afterwards destroying the waste with sulfuric acid. One day, he added too much sulfuric acid, which caused a cloud of purple vapour to form. He saw that it crystallized on cold surfaces, but he had no money to pursue the discovery. He passed some of the sample to chemist friends of his, who isolated the new element and determined its properties. The most well-known of these were Joseph Louis Gay-Lussac and Sir Humphrey Davy, both of whom claimed identification but credited Courtois with the discovery.