Term: isoelectronic
https://doi.org/10.1351/goldbook.I03276

Definition:
Two or more molecular entities are described as isoelectronic if they have the same number of valence electrons and the same structure, i.e. number and connectivity of atoms, but differ in some of the elements involved. Thus: CO, N2 and NO+ are isoelectronic. CH2=C=O and CH2=N=N are isoelectronic. CH3COCH3 and CH3N=NCH3 have the same number of electrons, but have different structures, hence they are not described as isoelectronic.


Related Terms:
1) molecular entities (http://doi.org/10.1351/goldbook.M03986).
2) connectivity (http://doi.org/10.1351/goldbook.C01274).
3) valence (http://doi.org/10.1351/goldbook.V06588).

Source: PAC, 1994, 66, 1077. 'Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)' on page 1128 (https://doi.org/10.1351/pac199466051077)

Citation: 'isoelectronic' 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.I03276

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