Illustrated Glossary of Organic Chemistry

Naked proton: H+. When an electron (e-) is removed from an atom of the most common hydrogen isotope (1H), only a naked proton (a proton with nothing else) remains. The symbol H+ implies a naked proton, although it is often used to mean aqueous H+, which case better symbols are H+(aq.), H3O+ (the hydronium ion), or H+(H2O)n. In general H+ is an accepted notation in introductory or general chemistry but not in organic chemistry. In organic chemistry "H+" can be used to indicate an unspecified acid (a proton source). A naked proton is a subatomic particle, which exists in places like interstellar space and physics textbooks, but not in solution chemistry.

This equilibrium for autoionization of water is imprecise because it implies the presence of a naked proton.

This equilibrium for autoionization of water is more precise because it implies the proton is bonded to at least one water molecule.