Hydrogen ion is recommended by IUPAC as a general term for all ions of hydrogen and its isotopes.^[1] Depending on the charge of the ion, two different classes can be distinguished:

Contents 1 Cation (positively charged) 2 Anion (negatively charged) 3 See also 4 References

[edit] Cation (positively charged)

Main article: hydron.

When hydrogen loses its electron, the following cations can be formed:

• Hydron: general name referring to the positive ion of any hydrogen isotope (H⁺)
• Proton: ¹H⁺ (most correctly, the cation of protium)
• Deuteron: ²H⁺, D⁺
• Triton: ³H⁺, T⁺

In addition, the ions produced by the reaction of these cations with water as well as their hydrates are called hydrogen ions:

• 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.

[edit] Anion (negatively charged)

Main article: hydrogen anion.

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^-

In organic chemistry, a hydrogen atom in a molecule is often referred to simply as a proton. The hydrogen anion has played an important role in quantum physics.

[edit] See also

• Acid
• pH
• Base (chemistry)

[edit] References