The cscl melting point is higher than the KCl melting point.
Why is this?
The cscl melting point is high because of the covalent bonding that occurs between the cation and anion. The covalent bonding is more stable than the ionic bonding in both substances, so it releases more energy as the crystal forms.
It is important to note that a lot of things influence the lattice energy of an ionic solid. For instance, the size of the cation, ionic radius, charge of the cation, etc. These factors are important to understand because they will affect the melting point of a substance.