Which of the following terms refers to a negatively charged ion?

An anion is a term used to describe a negatively charged ion. This occurs when an atom or molecule gains one or more electrons, giving it an excess of negative charge. For example, when a chlorine atom (which has 17 electrons) gains an additional electron, it becomes a chloride ion (Cl⁻), which is an anion.

In contrast, a cation refers to a positively charged ion, formed when an atom or molecule loses electrons. Atoms are neutral entities, so they do not carry a charge unless they gain or lose electrons. Electrons themselves are subatomic particles that carry a negative charge, but they are not ions; rather, they are part of what makes up ions when combined with atoms that have lost or gained electrons. This distinction clarifies why 'anion' is the correct response in identifying a negatively charged ion.