Definition of hydronium ion in English:

hydronium ion

Syllabification: hy·dro·ni·um i·on
Pronunciation: /hīˌdrōnēəm ˈīˌän


  • The ion H3O+, consisting of a protonated water molecule and present in all aqueous acids.
    More example sentences
    • Some examples of positively charged electrophiles are the hydronium ion, nitronium ions, metal ions, and carbocations.
    • In response to that stress, the conjugate base reacts with the hydronium ion, producing more carbon dioxide which is removed from the system by increasing respiration.
    • Metals high on the activity series react more vigorously with oxidants including the halogens and the hydronium ion than those lower on the scale.


early 20th century: hydronium, from German (a contraction).

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