Group 17 (Halogens)

Group 17, known as the halogens, includes five elements: fluorine, chlorine, bromine, iodine, and astatine. These elements are highly reactive nonmetals that readily form compounds with metals and other elements. They are called "halogens" because they produce salts when combined with metals. Halogens exist in different states: fluorine and chlorine are gases, bromine is a liquid, and iodine and astatine are solids. They are used in disinfectants, water treatment, and are important in chemistry and industry. Their reactivity decreases down the group, with fluorine being the most reactive.