Hydron (chemistry) - History of The Term

History of The Term

The term "hydron" is recommended by IUPAC to be used instead of "proton" if no distinction is made between the isotopes proton, deuteron and triton, all found in naturally occurring undifferentiated isotope mixtures. The name "proton" refers to isotopically pure 1H+. On the other hand, referring to the hydron as simply hydrogen ion is not recommended because hydrogen anions also exist.

The term "hydron" was defined by IUPAC in 1988. Traditionally, the term "proton" was and is used in place of "hydron". The latter term is generally only used in the context where comparisons between the various isotopes of hydrogen is important (as in the kinetic isotope effect or hydrogen isotopic labeling). Otherwise, referring to hydrons as protons is still considered acceptable, for example in such terms as protonation, deprotonation, proton pump or proton channel. The transfer of H+ in an acid-base reaction is usually referred to as proton transfer. Acid and bases are referred to as proton donors and acceptors correspondingly.

However, although 99.9844% of natural hydrogen nuclei are protons, the remainder (about 156 per million in sea water) are deuterons (see deuterium). A rare triton also occurs (see tritium).