Halogen
The halogens or halogen elements are a series of nonmetal elements from group 17 of the periodic table (formerly: VII, VIIA), comprising fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At). The artificially created element 117 (ununseptium) may also be a halogen.
The group of halogens is the only periodic table group which contains elements in all three familiar states of matter at standard temperature and pressure.
Read more about Halogen: History and Etymology, Group Trends, Diatomic Halogen Molecules, Production, Biological Role, Toxicity