The periodic table’s group 17 is known as the “halogens.” Fluorine, chlorine, bromine, iodine, and astatine are examples of halogens. They are extremely reactive nonmetals that combine with metals to generate salts. Halogens exist naturally as diatomic molecules in their elementary state. For example, fluorine is denoted as F2, chlorine as Cl2, bromine as Br2, and iodine as I2.