Question

The correct ionic radii order is :

• A. $N^{3-}>O^{2-}>F^{-}>N{a}^{+}$
• B. $N^{3-}>N{a}^{+}>O^{2-}>F^{-}$
• C. $N{a}^{+}>O^{2-}>N^{3-}>F^{-}$
• D. $O^{2-}>F^{-}>N{a}^{+}>N^{3-}$

Answer 1

The correct option is A $N^{3-}>O^{2-}>F^{-}>N{a}^{+}$

We know that a cation is smaller than a neutral atom because of increased effective nuclear charge. Similarly an anion is larger than a neutral atom because of electron-electron repulsion.
Greater the magnitude of negative charge on an anion, greater will be the size of it.
Therefore, $N^{3-}>O^{2-}>F^{-}>N{a}^{+}$
Hence option A is the right answer.