Hydrogen ion

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: positively charged ions and negatively charged ions.

Under aqueous conditions found in biochemistry, hydrogen ions exist as the hydrated form hydronium, H₃O⁺, but these are often still referred to as "hydrogen ions" or even "protons" by biochemists.

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

Cation (positively charged)

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⁺ (i.e. 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⁺ (named for Georg Zundel)
• Eigen cation: H₉O₄⁺ (named for Manfred Eigen)

Zundel cations and Eigen cations play an important role in proton diffusion according to the Grotthuss mechanism.

In connection with acids, "hydrogen ions" typically refers 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 (H⁻)
• Deuteride: ²H⁻, D⁻
• Tritide: ³H⁻, T⁻

See also

• Acid
• Protonation
• Dihydrogen cation

References

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