Final answer:
MgO has the most negative lattice energy among the given options due to the high charge of its ions, Mg2+ and O2-, and the lattice energy being four times greater than that of salts with 1+ and 1- charged ions with similar sizes and distances.
Step-by-step explanation:
Among the given ionic solids, MgO (Magnesium Oxide) would have the most negative lattice energy. Lattice energy is a measure of the strength of the bonds holding ions together in a crystal lattice, and it is highly dependent on both the charges of the ions and the distance between them. The lattice energy increases significantly with the charge of the ions, and it decreases as the distance between the ions increases. Since MgO consists of Mg2+ and O2- ions, which both have a charge of ±2, it will have a lattice energy that is four times greater than a salt with ions of a ±1 charge, assuming comparable ion size and distances.
It is known from the provided information that the lattice energy of LiF is 1023 kJ/mol with ions having a ±1 charge and a small distance between them. As MgO crystallizes in the same structure and with a similar bond length, it would have a lattice energy that is much higher than that of LiF. Specifically, as both ions in MgO have twice the charge of those in LiF, and the bond length is similar, a quadrupling of the lattice energy is expected. This is supported by data indicating that the lattice energy of MgO is 4008 kJ/mol, which is close to four times that of LiF.