It is the least active of the halogens , which are found in group VIIa of the periodic table . It is normally diatomic, i.e., it has 2 iodine atoms in each molecule, in the solid, liquid, and vapor states. Iodine is only slightly soluble in water but dissolves readily in a solution of sodium or potassium iodide.
Tincture of iodine is a solution of iodine and potassium iodide in alcohol.
Iodine also dissolves in carbon disulfide, carbon tetrachloride, and chloroform, giving a deep violet solution. Iodine forms many compounds. With hydrogen it forms hydrogen iodide, which in water solution becomes hydriodic acid. Iodine is displaced from its compounds by the other halogens. The element is obtained from salt deposits, as from the saltpeter beds in Chile, where it occurs in small quantities as an iodate, and from the salt brines associated with some oil wells in California and Louisiana.