Question

Choose the correct order of covalent character:

• A. $KCl>AgCl$
• B. $MgO<Mg{F}_2$
• C. $K_{2}C{O}_3<A{g}_{2}C{O}_3$
• D. $LiBr>LiI$

Answer 1

The correct option is C $K_{2}C{O}_3<A{g}_{2}C{O}_3$

a) Due to the smaller size of $A{g}^{+}$, the polarising power of $A{g}^{+}$ is more compared to the $K^{+}$ ion, hence the covalent character of $AgCl$ is also more compared to $KCl$

b) $Mg{F}_2$ is more ionic compared to $MgO$ because the electronegativity difference between the atoms is more in $Mg{F}_2$ and along with that the size of $F^{-}$ ion is also smaller compared to $O^{2-}$ ion.

c) $K_{2}C{O}_3<A{g}_{2}C{O}_3$
Smaller the size of the cation, greater will be the polarizing power and hence greater the covalency of the compound.
Also $A{g}^{+}$ has a pseudo-inert gas configuration which imparts futher covalency to silver carbonate.

d) Again due to the larger size of $I^{-}$ ion compared to $B{r}^{-}$ ion, $I^{-}$ is more polarisable and thus $LiI$ has more covalent character.