Question

The ionic radii $\left(\right.\text{in} \, Å\left.\right)$ of $N^{3 -}, \, O^{2 -} \, $ and $ \, F^{-} \, $ are respectively:

• A. $1.71,1.36$ and $1.40$
• B. $1.36,1.40 $ and $1.71$
• C. $1.36,1.71$ and $1.40$
• D. $1.71,1.40$ and $1.36$

Answer 1

Answer: (D)

As $\frac{Z}{ e } \uparrow$ ionic radius decreases for isoelectronic species.
$Z=$ numberofprotonse $=$ numberofelectrons
$( N )^{3-}\left(\frac{ Z }{ e }\right)=\frac{7}{10}$
$( O )^{2-}\left(\frac{ Z }{ e }\right)=\frac{8}{10}$
$( F )^{-}\left(\frac{ Z }{ e }\right)=\frac{9}{10}$
Trend of ionic radius: $N ^{3-}> O ^{2-}> F ^{-}$