Question

Identify the correct order in which the ionic radius of the following ions increases.
$\left(I\right)F^{-}$
$\left(II\right)N{a}^{+}$
$\left(III\right)N^{3-}$

• A. $III,I,II$
• B. $I,II,III$
• C. $II,III,I$
• D. $II,I,III$

Answer 1

The correct option is D $II,I,III$

The species (atoms or ions) having the same number of electrons are known as iso-electronic species. In iso-electronic species, the size increases with the increase of negative charge and decrease of positive charge.
$(size\propto \frac{1}{z/eratio})$. i.e. effective nuclear charge.
Decreasing order of size.
$C^{4-}>N^{3-}>O^{2-}>F^{-}>Ne>N{a}^{+}>M{g}^{2+}>A{l}^{3+}>S{i}^{4+}$