The halogens are found in Group 17 of the periodic table. This group is located in the second column from the right, next to the noble gases group. The halogens include the elements fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and the radioactive astatine (At) and tennessine (Ts), though the latter two are sometimes excluded due to their unique properties. The group is characterized by elements that are highly reactive nonmetals with seven valence electrons, making them one electron short of a full octet and giving them strong reactivity. The term "halogen" means "salt former," as these elements readily form salts when reacting with metals. Group 17 is also known as Group VIIA in older classification systems.