Question

The ions $O^{2-},F^{-},N{a}^{+},M{g}^{2+},$and $A{l}^{3+}$ are isoelectronic, Their ionic radii show:

• A. An increase from $O^{2-}to{F}^{-}$ and then decrease from $N{a}^{+}toA{l}^{3+}$
• B. A decrease from $O^{2-}to{F}^{-}$ and then an increase from $N{a}^{+}toA{l}^{3+}$
• C. A significant increase from $O^{2-}toA{l}^{3+}$
• D. A significant decrease from $O^{2-}toA{l}^{3+}$

Answer 1

The correct option is D A significant decrease from $O^{2-}toA{l}^{3+}$

In the case of isoelectronic species, more the effective nuclear charge, less is the size. Here from $O^{2-}toA{l}^{3+}$ the effective nuclear charge increases and the radii goes on decreasing.