hydronium

hydro- +‎ onium

hydronium (plural hydroniums)

1. (inorganic chemistry, physical chemistry) The hydrated hydrogen ion, H₃O⁺.
   • 1996, Richard I. Masel, Principles of Adsorption and Reaction on Solid Surfaces, Wiley, page 148:

     The case of hydronium ions (H₃O⁺) is an example of this. In the gase^[sic] phase, hydronium is a weak acid. The data in Table 3.10 indicates that bare hydronium ions have a higher electron affinity than most metal surfaces, so a bare hydronium ion should be neutralized when it absorbs on a bare metal surface. However, a hydrated hydronium ion is a stronger acid.

   • 2006, Johanna Holm, Forgotten Chemistry: A Refresher Course, Barron's Educational Series, page 160:

     Acids are compounds that produce hydronium ions when mixed with water. […] The hydronium ion is a very special ion because it is the defining particle of all acids.

   • 2016, Philippe Deprez, Textbook of Chemical Peels: Superficial, Medium, and Deep Peels in Cosmetic Practice, 2nd edition, Taylor & Francis (CRC Press), page 48:

     Hydronium is not a way of stabilizing an acid, because the structure itself is so quickly transient that it can be considered as not existing.

   • 2016, Andrés G. Muñoz, Photoelectrochemical Solar Conversion Systems: Molecular and Electronic Aspects‎, Taylor & Francis (CRC Press), page 206:

     There is experimental evidence for the formation of coordination groups of hydroniums with several water molecules by hydrogen bridges.

May also be defined as the simplest of a class of oxygen cations with three bonds (i.e., the simplest form of oxonium).

• (hydrated hydrogen ion): hydronium ion

• (cation of oxygen): oxonium

• hydroxide
• hydrogen ion

• Self-ionization of water on Wikipedia.Wikipedia