Term: ionic bond
https://doi.org/10.1351/goldbook.IT07058

Definition:
The bond between atoms with sharply different electronegativities. In strict terms, an ionic bond refers to the electrostatic attraction experienced between the electric charges of a cation and an anion, in contrast with a purely covalent bond. In practice, it is preferable to consider the amount of ionic character of a bond rather than referring to purely ionic or purely covalent bonds. The relationship was proposed (L. Pauling) for the estimation of ionic character of a bond between atoms A and B: \[\text{Amount of ionic character} = 1 - e^{-1/4}\ (\chi _{\text{A}}\,-\,\chi_{\text{B}})\] where χ A and χ B are the Pauling electronegativities of atoms A and B. This type of bonding is realized mostly in solids.

Related Terms:
1) cation (http://doi.org/10.1351/goldbook.C00907).
2) anion (http://doi.org/10.1351/goldbook.A00358).
3) covalent bond (http://doi.org/10.1351/goldbook.C01384).
4) electronegativities (http://doi.org/10.1351/goldbook.E01990).

Source: PAC, 1999, 71, 1919. 'Glossary of terms used in theoretical organic chemistry' on page 1947 (https://doi.org/10.1351/pac199971101919)

Citation: 'ionic bond' 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.IT07058

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