Question

Which is more ionic $\mathrm{NaCl}\mathrm{or}\mathrm{KCl}$?

Answer 1

1. Sodium and Potassium is the chemical elements present in group 1 of the periodic table.
2. The atomic number of Sodium is $11$and to that of Potassium is$19$.
3. Sodium and Potassium both forms cations.
4. The ionic characters will be based on the size of the cation.
5. The polarising power of cation is inversely proportional to the ionic radius.$\mathrm{Polarising}\mathrm{power}\mathrm{of}\mathrm{cation}\propto \frac{1}{\mathrm{Ionic}\mathrm{radius}}$
6. Greater is the size of the cation, more will be the ionic radius and lesser is the polarizing power.
7. We know that the size of elements increases as we move down the group.
8. This implies that the element present bottom of the group have the largest ionic radius compared to the elements present at top.
9. The order of the size of cation of group 1 elements are ${\mathrm{Na}}^{+}<{\mathrm{K}}^{+}<{\mathrm{Rb}}^{+}<{\mathrm{Cs}}^{+}<{\mathrm{Fr}}^{+}$.
10. The cation of Sodium is smaller compared with Potassium and so the ionic radius of Potassium is bigger.
11. Bigger is the ionic radius of Potassium lesser will be the polarising power and so it becomes more ionic in nature.
12. Thus, we concluded that $\mathrm{KCl}$ is more ionic compared with $\mathrm{NaCl}$.