Anion

Definition

A negatively charged ion formed when an atom gains one or more electrons, leaving it with more electrons than protons.

Chlorine becomes chloride (Cl-) by accepting an electron to complete its octet, and the name change signals that it has been ionized. Elements with five, six, or seven valence electrons tend to gain or share electrons and form anions. Carbonate behaves externally as a doubly charged anion despite being held together internally by covalent bonds.

Related concepts

Cation · Ionic bond · Valence electrons

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Part of The Blueprint of Water · 🧪 chemistry