Question

when an atom gains an electron, the resulting particle is called: an anion. a cation. an isotope. a proton. none of the above

Explanation:

An atom that gains an electron has more electrons than protons, resulting in a negative charge. An anion is a negatively - charged ion. A cation is a positively - charged ion (formed when an atom loses an electron). An isotope is an atom of the same element with a different number of neutrons. A proton is a sub - atomic particle in the nucleus of an atom.

Answer:

an anion