Halogens form negatively charged ions known as halides. These ions are formed when a halogen atom gains one electron to achieve a stable electron configuration. The halogens are found in Group 17 of the periodic table, and they have seven valence electrons. By gaining one electron, they complete their outer shell, resulting in a stable octet configuration.
For example, chlorine (Cl) gains one electron to form a chloride ion (Cl⁻). Similarly, fluorine (F) forms a fluoride ion (F⁻), and bromine (Br) forms a bromide ion (Br⁻). These halide ions are essential in various chemical reactions and are commonly found in salts, such as sodium chloride (NaCl).
In summary, halogens form halide ions by gaining one electron, which allows them to achieve a stable electron configuration.