Explain why the lattice energy of MgS is approximately four times as large as that of NaCl?

The lattice energy of MgS is 4 times larger than that of NaCl because,

• MgS has a higher charge that is $M{g}^{2+},S^{2-}$ than NaCl $\left(N{a}^{+},C{l}^{-}\right)$ .

• Higher charge indicates it has stronger bonds. This is because charge and force are directly related to each other in the coulombic force equation.
• Also, the force of attraction is directly proportional to the product of charges of constituent ions.
• Here, in MgS the product of charge is 4 times higher than NaCl so as the lattice energy.

The formation of one mole of an ionic compound from its gaseous ions requires a certain amount of energy. This energy is lattice energy. The charge of the ions that constitute is directly dependent on lattice energe, as the charge increase lattice energy also increases. Another property is the size of the ion, as the size increase lattice energy decreases.