What does the term isoelectron refer to?

The term isoelectron refers to atoms or ions that have the same number of electrons. This concept is significant in chemistry because it highlights how different elements can exhibit similar electronic structures, despite having different atomic numbers.

When two atoms or ions have the same number of electrons, they may display similar chemical properties, particularly when it comes to how they bond and interact with other atoms. This concept is particularly useful in the study of ions, as for example, the sodium ion (Na⁺) and neon (Ne) both have ten electrons in common, despite being very different elements with their unique properties.

In contrast, atoms with different atomic numbers will inherently have different numbers of protons, which can affect their overall charge and identity, thus they cannot be considered isoelectronic if their electron counts differ. Similarly, atoms of the same element cannot be classified as isoelectronic because they have identical electronic configurations by definition. Lastly, molecules with no charge are not relevant to the definition of isoelectronic species, as the focus is solely on the electron count regardless of molecular charge.