Question

$O^{2-}$and $S{i}^{4+}$ are isoelectronic ions. If the ionic radius of $O^{2-}$ is $1A^{\circ }$, the ionic radius of $S{i}^{4+}$ will be:

• A. $1.4A^{\circ }$
• B. $0.41A^{\circ }$
• C. $2.8A^{\circ }$
• D. $1.5A^{\circ }$

Answer 1

The correct option is B $0.41A^{\circ }$

$O^{2-}$ and $S{i}^{4+}$ have 10 electrons each. Thus they are isoelectronic.

For iso-electronic species, atomic radius is inversely proportional to Z effective. Z effective is directly proportional to the positive charge.

More the positive charge more the Z effective. $S{i}^{4+}$ has +4 charge so it will have a shorter radius than $O^{2-}$.

Hence option B is correct.