# Which one of the following ions has the highest value of ionic radius? Option 1) $Li^{+}\;$ Option 2) $\; B^{3+}\;$ Option 3) $\; O^{2-}\;$ Option 4) $\; F^{-}$

As we learnt in

The ionic radius is the distance between the nucleus of an ion and the point where the nucleus exerts its influence on the electron cloud.

$r_{cation}+r_{anoin}=r_{ionic \:\:radii}$

-

and,

Radius of cation -

Radius of a cation is invariably smaller than that of the corresponding neutral atom.

- wherein

$Na(1s^{2}2s^{2}2p^{6}3s^{1}), \;Na^{+}(1s^{2}2s^{2}2p^{6})$

and again,

Radius of anion -

Radius of an anion is invariably bigger than that of the corresponding atom.

- wherein

$Cl(1s^{2}2s^{2}2p^{6}3s^{2}3p^{5}), \;Cl^{-}(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6})$

As the  $\frac{z}{e}$    ratio increases, the size decreases and vice versa.

For  $Li^{+},\:\:\frac{z}{e}=\frac{3}{2}=1.5$

For  $F^{-},\:\:\frac{z}{e}=\frac{9}{10}=0.9$

For  $O^{2-},\:\:\frac{z}{e}=\frac{8}{10}=0.8$

For  $B^{3+},\:\:\frac{z}{e}=\frac{5}{2}=2.5$

Option 1)

$Li^{+}\;$

This option is incorrect.

Option 2)

$\; B^{3+}\;$

This option is incorrect.

Option 3)

$\; O^{2-}\;$

This option is correct.

Option 4)

$\; F^{-}$

This option is incorrect.

### Preparation Products

##### JEE Main Rank Booster 2021

This course will help student to be better prepared and study in the right direction for JEE Main..

₹ 13999/- ₹ 9999/-
##### Knockout JEE Main April 2021 (Subscription)

An exhaustive E-learning program for the complete preparation of JEE Main..

₹ 4999/-
##### Knockout JEE Main April 2021

An exhaustive E-learning program for the complete preparation of JEE Main..

₹ 22999/- ₹ 14999/-
##### Knockout JEE Main April 2022

An exhaustive E-learning program for the complete preparation of JEE Main..

₹ 34999/- ₹ 24999/-