Iodine is a chemical element with the symbol I and atomic number 53. It is a nonmetal and a halogen that appears as a lustrous blackish-gray solid at room temperature and pressure, but sublimes readily to a violet-colored gas.
It is rare to find elemental iodine in its pure form as a black solid, as it tends to quickly sublime to a gas. However, iodine can be found in a variety of compounds, including iodides, iodates, and organoiodine compounds. These compounds are widely used in a variety of applications, including as disinfectants, contrast agents in medical imaging, and in the production of dyes, pigments, and pharmaceuticals.