a negatively-charged particle. It is a type of ion (charged particle), and it’s “opposite” is the cation, which is positively-charged. The charge comes from having more electrons (-) than protons (+) and can be associated with a single atom (such as Cl⁻) or a larger molecule (polyatomic ions such as PO₄³⁻). The “# of charges” is referred to as the valency. So, for example, Cl⁻ is monovalent and PO₄³⁻ is trivalent. Anions are attracted to cations and can form strong non-covalent bonds referred to as “ionic bonds” or “salt bridges.”