Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025
Definition
An ion is an atom or molecule that has gained or lost one or more electrons, resulting in a net electric charge. Ions can be either positively charged (cations) or negatively charged (anions).
5 Must Know Facts For Your Next Test
Ions are formed when atoms gain or lose electrons to achieve a more stable electron configuration.
Cations are positively charged ions formed by the loss of electrons.
Anions are negatively charged ions formed by the gain of electrons.
Ions play crucial roles in chemical reactions, especially in the formation of ionic bonds.
The charge of an ion is indicated by a superscript number and sign (e.g., Na$^+$, Cl$^-$).