Term: ionization
https://doi.org/10.1351/goldbook.I03183

Definition:
The generation of one or more ions. It may occur, e.g. by loss of an electron from a neutral molecular entity, by the unimolecular heterolysis of such an entity into two or more ions, or by a heterolytic substitution reaction involving neutral molecules, such as: I03183-1.png I03183-2.png I03183-3.png The loss of an electron from a singly, doubly, etc. charged cation is called second, third, etc. ionization. This terminology is used especially in mass spectroscopy.

Related Terms:
1) dissociation (http://doi.org/10.1351/goldbook.D01801).
2) ionization energy (http://doi.org/10.1351/goldbook.I03199).
3) molecular entity (http://doi.org/10.1351/goldbook.M03986).
4) unimolecular heterolysis (http://doi.org/10.1351/goldbook.M03989).
5) substitution reaction (http://doi.org/10.1351/goldbook.S06078).
6) cation (http://doi.org/10.1351/goldbook.C00907).
7) mass spectroscopy (http://doi.org/10.1351/goldbook.M03748).

Images:
1) Not defined (https://goldbook.iupac.org/img/inline/I03183-1.png) 
2) Not defined (https://goldbook.iupac.org/img/inline/I03183-2.png) 
3) Not defined (https://goldbook.iupac.org/img/inline/I03183-3.png) 

Source: PAC, 1994, 66, 1077. 'Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)' on page 1127 (https://doi.org/10.1351/pac199466051077)

Citation: 'ionization' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.I03183

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