Final answer:
The lattice energy of an ionic compound is the energy required to separate one mole of the solid into its component gaseous ions, and it is always a positive number. Lattice energy can be estimated using the Born-Haber cycle or by calculating it based on the crystal structure's electrostatic considerations.
Step-by-step explanation:
The lattice energy (AHlattice) of an ionic compound is defined as the energy required to separate one mole of the solid into its component gaseous ions. It is always a positive number. Lattice energy cannot be measured directly but can be estimated using the Born-Haber cycle or by calculating it from the electrostatic considerations of the crystal structure. Higher lattice energies indicate more stable ionic compounds.