The Group 17 elements, known as halogens, include fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At). These elements are characterized by having seven valence electrons, arranged in a way that they need just one additional electron to complete their outer shell and achieve a stable configuration similar to noble gases. The outermost electron configuration of halogens is ns²np⁵, where n corresponds to the principal quantum number of the outer shell.