How is a molecule classified that contains a negative electrical charge?

A molecule that contains a negative electrical charge is classified as an anion. This classification arises from the molecule gaining one or more electrons, which results in an excess of negatively charged particles. Anions play a crucial role in various chemical reactions and processes, especially in the context of solutions where they can interact with cations—positively charged ions—leading to the formation of salts and other compounds.

In contrast, cations are positively charged ions, formed when atoms or molecules lose electrons. Molecule ions are combinations of atoms that can carry either a positive or negative charge, but specifically, when referring to a negatively charged molecule, the term used is anion. Radicals are molecules that contain unpaired electrons, leading to high reactivity, but do not necessarily imply a net negative charge. Each of these classifications serves distinct roles in chemistry, but for a negatively charged molecule, anion is the appropriate term.