Final answer:
Lattice energy is key to the stability of ionic compounds, with compounds containing higher-valence ions having greater lattice energy. Ionic sizes, charge densities, and crystal structure also influence lattice energy, as calculated by the Born-Haber cycle.
Step-by-step explanation:
The lattice energy is a critical factor affecting the stability of an ionic compound. It is defined as the energy required to separate one mole of an ionic solid into its component gaseous ions. Ionic compounds with higher-valence ions (di- or tripositive cations and anions) have higher lattice energies due to the product of the ionic charges, resulting in stronger electrostatic attractions within the crystal lattice.
Factors such as ionic sizes, charge densities, and the crystal structure also play a significant role in determining the lattice energy. Larger ions with smaller charge densities result in lower lattice energies since the ions can be more easily separated. Crystal structures that allow for maximum ion contact will increase the lattice energy.
The Born-Haber cycle, incorporating Hess's law, is used for the indirect calculation of lattice energy, which is not directly measurable. This cycle relates the lattice energy to the enthalpy of formation and other thermochemical quantities.