Which is more ionic $\mathrm{LiF}\mathrm{and}\mathrm{CsF}$?

1. Lithium and Cesium belong to first group of the periodic table.
2. Lithium is smaller in size whereas Cesium is bigger in size and this is due to an increase in the atomic number and size as we go downwards in the group.
3. Fluorine is common in both the elements and it form anion by losing the electrons.
4. Fluorine is the most electronegative element of the periodic table whereas Cesium and Lithium are electropositive in nature.
5. The electropositivity will also increases as we move down the group and this suggests that Cesium is much more electropositive compared with Lithium.
6. Ionic characters are directly proportional to the electronegative difference between the elements.
7. This implies that more electronegative Fluorine and more electropositive Cesium has a bigger electronegative difference between them.
8. Hence, we concluded that Lithium Fluoride is less ionic than Cesium Fluoride.