When Group 7 elements react, do they gain or lose electrons?

• A. Lose one electron
• B. Gain one electron
• C. Lose two electrons
• D. Gain two electrons

Answer: (B)

Group 7 elements have seven electrons in their outer shell, so they aim for a full outer shell of eight. Gaining one electron completes that shell, giving them a stable octet and a negative charge (-1). That’s why, in reactions with metals, they effectively accept one electron from the metal to form ions like Cl−, Br−, etc. Losing electrons would leave them with a deficient octet and a positive charge, which is not how they typically behave. Gaining two electrons would give a -2 charge, which is not the usual form for these elements. So the common outcome is gaining one electron to achieve a stable configuration.