Question

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

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

Answer 1

Answer: (D)

Ionic radii
$\propto \frac{1}{effectivenuclearch\arg e(Z_{eff})}$
$\propto negativecharge$
$\propto \frac{1}{positivecharge}$
Hence, as the negative charge increases, ionic radii increases and with increase in positive charge ionic radii decrease. Hence, ionic radii decreases from
$N^{3-}$ to $M{g}^{2+}$