What is an atom that has more electrons than normal referred to as?

An atom that has more electrons than normal is referred to as a negative ion. It has more negative electric charge from electrons than positive charge from protons, giving it an overall negative charge. The scientific term for this type of ion is an anion.

A neutral atom normally contains equal numbers of protons and electrons. If it gains one or more electrons, that balance changes. For example, a chlorine atom can gain one electron to become a chloride ion, written Cl⁻. The extra electron does not change the atom’s element; chlorine remains chlorine because its number of protons is unchanged.

This is different from a positive ion, or cation, which forms when an atom loses electrons. The terms “negative ion” and “anion” describe the same basic electrical condition, although “anion” is the more specialized chemistry term.

Negative ions are important in ionic compounds. Sodium, for example, loses an electron to form Na⁺, while chlorine gains one to form Cl⁻; their opposite charges attract to form sodium chloride.