Cation (positively charged)
- Hydron: general name referring to the positive ion of any hydrogen isotope (H+)
- Proton: 1H+
- Deuteron: 2H+, D+
- Triton: 3H+, T+
- Hydronium ion: H3O+
- Zundel cation: H5O2+
- Eigen cation: H9O4+
The latter two play an important role in proton hopping according to the Grotthuss mechanism.
In connection with acids, hydrogen ions typically refer to hydrons.
Anion (negatively charged)
Hydrogen anions are formed when additional electrons are acquired:
- Hydride: general name referring to the negative ion of any hydrogen isotope
- Deuteride: 2H-, D-
- Tritide: 3H-, T-
- Compendium of Chemical Terminology, 2nd edition McNaught, A.D. and Wilkinson, A. Blackwell Science, 1997 [ISBN 0-86542-684-8], also online