Explain the variation of radii of is electronic species or ions.

Explanation

With in the series of iso electronic ions , as the nucleus charge increase , the attractive force between the electrons and nucleus , also increase . Thus results in the decrease of ionic radius . In other words , size of the isoelectronic ions decreases with the increase in the magnitude of nuclear change .
Ex: - `N^(3-),O^(2-),F^(-),Na^(+),Mg^(2+),Al^(3+)` Are isoelectronic and have 10 electrons cache. The size of these ions are in the order :
`Mg^(2+)ltNa^(+)ltF^(-)ltO^(2-)ltN^(3-)`
Mg having highest nuclear change. (12 units) has the smallest size whereas `N^(3-)`
ion having the smallest nuclear change ( 7 units ) has the largest size.