Answer
When an anion is formed, radius increases due to greater electron-electron repulsion, and when a cation is formed, radius decreases for the same reason.
Isoelectronic: Two particles are isoelectronic if they have the same electron configuration (for example Li+ cation and He are isoelectronic).
The ion with the smallest radius in an isoelectronic series is the one with the greatest number of protons, as this maximizes nuclear attraction.
Work Step by Step
See above
