Which ions lose electrons at the anode?

• A. Negative ions
• B. Positive ions
• C. Hydrogen ions
• D. Metal ions

Answer: (A)

At the anode, oxidation happens. The electrode there is the site where electrons are removed from species. Negatively charged ions move toward the anode and lose electrons as they are oxidized, turning into neutral atoms or molecules. That’s why negative ions are the ones that undergo oxidation at the anode.

Positive ions, on the other hand, move toward the cathode and gain electrons (reduction). Hydrogen ions are positive and are typically reduced at the cathode to form hydrogen gas, not oxidized at the anode. Metal ions are also positively charged and are usually reduced at the cathode to become metal atoms. So the only ions that lose electrons at the anode are the negative ions.