Lattice Energy Calculator

Lattice energy is the energy required to completely separate one mole of an ionic solid into gaseous ions, or the energy released when gaseous ions combine to form one mole of an ionic solid. It measures the strength of ionic bonding and determines properties like melting point, solubility, and hardness.

The Born-Landé equation is a theoretical model that calculates lattice energy using ionic charges, distances, and crystal structure constants. The Born-Haber cycle is an experimental approach using measured thermodynamic data like formation enthalpy, ionization energy, and electron affinity.

The Madelung constant depends on crystal structure: NaCl structure = 1.748, CsCl structure = 1.763, CaF₂ structure = 2.519, Al₂O₃ structure = 4.172. It represents the geometric arrangement of ions in the crystal lattice.

Lattice energy increases with higher ionic charges (z₊ × z₋) and decreases with larger ionic distances (r₀). Small, highly charged ions like Mg²⁺ and O²⁻ in MgO produce very high lattice energies compared to large, singly charged ions like Cs⁺ and I⁻.

The Born exponent (n) represents the repulsive forces between ions. Typical values: He configuration = 5, Ne = 7, Ar = 9, Kr = 10, Xe = 12. For mixed configurations, use the average or consult literature values for your specific compound.

The Born-Landé equation assumes perfect ionic bonding and point charges, while real crystals have some covalent character and polarization effects. Born-Haber cycle uses experimental data reflecting actual bonding, so differences indicate deviations from the ideal ionic model.

Lattice energies vary widely: NaCl ≈ 786 kJ/mol, MgO ≈ 3795 kJ/mol, CaF₂ ≈ 2630 kJ/mol. Compounds with doubly charged ions (like MgO) have much higher values than singly charged ions (like NaCl) due to the z₊ × z₋ relationship.