Chlorine belongs to the halogen group in the periodic table. It has an atomic number of 17, which indicates the number of protons and electrons in a neutral atom of chlorine is 17.
Therefore; with an atomic number of 17, its electronic configuration will be 2:8:7.
Thus; to attain a stable configuration chlorine requires to gain one electron, by so doing it becomes a negatively charged ion with a charge of -1.
