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Which one of the following ions has the highest value of ionic radius?

  • Option 1)


  • Option 2)

    \; B^{3+}\;

  • Option 3)

    \; O^{2-}\;

  • Option 4)

    \; F^{-}


Answers (1)


As we learnt in 


Ionic Radii -

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}






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)


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.

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