Iodine is element 53, a halogen of the p block, in group 17, period 5. Its ground-state configuration is [Kr] 4d10 5s2 5p5, and it usually shows the oxidation states -1, 0, 1, 3, 5, 7.
It was discovered in 1811, by Courtois.
Name origin: French iode (after the Greek ioeides, 'violet').
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