Hydronium vs. Hydroxide — What's the Difference?

In chemistry, hydronium (hydroxonium in traditional British English) is the common name for the aqueous cation H3O+, the type of oxonium ion produced by protonation of water. It is often viewed as the positive ion present when an Arrhenius acid is dissolved in water, as Arrhenius acid molecules in solution give up a proton (a positive hydrogen ion, H+) to the surrounding water molecules (H2O).

Hydroxide is a diatomic anion with chemical formula OH−. It consists of an oxygen and hydrogen atom held together by a single covalent bond, and carries a negative electric charge.

A hydrated hydrogen ion, H3O+. Also called hydronium ion.

A chemical compound, especially an ionic compound, containing a hydroxyl group.

(inorganic chemistry) The hydrated hydrogen ion, H₃O⁺.

(chemistry) An univalent anion (OH^-) based on the hydroxyl functional group.

Any substance containing such an anion.

A hydrate; a substance containing hydrogen and oxygen, made by combining water with an oxide, and yielding water by elimination. The hydroxides are regarded as compounds of hydroxyl, united usually with basic element or radical; as, calcium hydroxide ethyl hydroxide.

A compound of an oxide with water

A chemical compound containing the hydroxyl group