What are isoelectronic species and give examples?

Isoelectronic species

• Isoelectronic species are atoms and ions that have the same number of electrons.
• Or, A pair of species having the same number of electrons combining all the atoms of a particular species is called an isoelectronic pair.
• Because of different nuclear charges, the radii of isoelectronic species would differ.

Examples

${\mathrm{O}}^{2-}$:-In this given species, the number of electrons would be $10$ that is $\left(8+2=10\right)$.

${\mathrm{F}}^{-}$ :-In this given species, the number of electrons would be $10$ that is $\left(9+1=10\right)$.