Illustrated Glossary of Organic Chemistry

Ionization: Any chemical process resulting in one or more ions. Often due to the heterolytic cleavage of one or more covalent bonds. A salt does not undergo ionization by dissociation of the anion and cation because in this case the ions are already ions and not associated by a covalent bond.

Ionization of tert-butyl bromide yields tert-butyl carbocation and bromide ion.

Ionization of this oxonium ion yields benzyl carbocation and a molecule of water.

In mass spectrometry, electron impact ionization is a useful way to generate a radical cation molecular ion.