Question

There is a general understanding of ionic radius based on the nuclear charges-and the number of electrons surrounding the nucleus which generally works very well. Which one of the following represents the correct decreasing order of ionic radius for $C^{4-},N^{3-},O^{2-}$ and $F^{-}$ ?

• A. $C^{4-}>N^{3-}>O^{2-}>F^{-}$
• B. $F^{-}>O^{2-}>N^{3-}>C^{4-}$
• C. $O^{2-}>N^{3-}>C^{4-}>F^{-}$
• D. $F^{-}>N^{3-}>C^{4-}>O^{2-}$

Answer 1

The correct option is A $C^{4-}>N^{3-}>O^{2-}>F^{-}$

The ionic radii of isoelectronic ions decreases with the increase in the magnitude of nuclear charge, because the force of attraction by the nucleus on the electrons also increases. Thus, the correct decreasing order of ionic radii
$C^{4-}>N^{3-}>O^{2-}>F^{-}$