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The term isoelectronic is applied to two or more atoms, ions, or molecules that have the same number and structure of valence electrons. It literally means “equal number of electrons.” Isoelectronic chemical species have similar chemical properties. Atoms or molecules with the same valence electron configurations are then said to be isoelectronic, or to have the same isoelectronicity.
Examples of isoelectronic chemical species
The K + ion is isoelectronic with the Ca 2+ ion . The carbon monoxide (CO) molecule is isoelectronic with nitrogen gas (N 2 ) and with the nitrosonium ion (NO + ). The organic molecules CH 2 =C=O and CH 2 =N=N are isoelectronic.
By contrast, the organic molecules CH 3 COH 3 and CH 3 N=NCH 3 are not isoelectronic. They have the same number of electrons but different valence electron structures.
The amino acids cysteine, serine, tellurocysteine, and selenocysteine are isoelectronic, having the same valence electron structure.
More examples of ions and isoelectronic elements
| Ions/isoelectronic elements | Electronic configuration |
|---|---|
| Hey Li + | 1s2 |
| Hey, Be 2+ | 1s2 |
| Ne, F – | 1s2 2s2 2p6 |
| Na + , Mg 2+ | 1s2 2s2 2p6 |
| K, Ca 2+ | [Ne] 4s1 |
| Ar, S2- | 1s2 2s2 2p6 3s2 3p6 |
| S2- , P3- _ | 1s2 2s2 2p6 3s2 3p6 |
Applications of isoelectronicity
Isoelectronicity can be used to predict the chemical properties and reactions of an atom or a molecule. It is used to identify atoms with chemical properties similar to hydrogen, which has one valence electron, and therefore should be isoelectronic with respect to hydrogen. The procedure can be applied to predict or identify the chemical properties of unknown or unusual compounds, based on the resemblance of their electronic structure to known chemical species.
References
- https://glosarios.servidor-alicante.com/quimica/isoelectronico
- https://www.profesor10demates.com/2021/11/radio-ionico-y-sustancias-isoelectronicas-ejercicos-resueltos-%F0%9F%91%88.html
