Which one of the following has the highest lattice energy?

Explanation

The lattice energy is the enthalpy change involved in the formation of an ionic compound from gaseous ions. The lattice energy is directly proportional to the charge of the ions, but inversely proportional to the radii of the ions. As we go down in the group, I and VII, in this case, the ionic radius increases, while the charge is constant. Therefore, the lattice energy of the compounds decreases. The order of increasing radius (decreasing lattice energy) for cations: Li> Na> K The order of increasing radius (decreasing lattice energy) for anions: F> Cl> Br Hence the compound lithium chloride will have the greatest lattice energy as both the ions have the smallest radius. Note. From left to right, as the charge on the ion increases, the lattice energy increases.