Iodine

**Definition:** A nonmetallic element of the halogen group that is represented by the atomic symbol I, atomic number 53, and atomic weight of 126.90. It is a nutritionally essential element, especially important in thyroid hormone synthesis. In solution, it has anti-infective properties and is used topically.

**Tree numbers:** - D01.268.380.400

**Synonyms:** - Iodine-127