What are the elements of group 17 (fluorine, chlorine, bromine, iodine, and astatine) called?
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halogens
The elements of Group 17 (fluorine, chlorine, bromine, iodine, and astatine) are called the halogens . The halogens all have the general electron configuration n s 2 n p 5 , giving them seven valence electrons. They are one electron short of having full outer s and p sublevels, which makes them very reactive. They undergo especially vigorous reactions with the reactive alkali metals. In their pure elemental forms, chlorine and fluorine are gases at room temperature, bromine is a dark orange liquid, and iodine is a dark purple-gray solid. Astatine is so rare that its properties are mostly unknown.