Lattice Energy Calculator

Lattice energy measures the strength of the ionic bonds holding a crystal together — the energy released when gaseous ions form one mole of an ionic solid. Select a Calculation Method (Born-Landé Equation or Born-Haber Cycle), then enter the corresponding parameters — such as Madelung constant, ion charges, and interionic distance for Born-Landé, or thermochemical values like formation enthalpy and ionization energy for Born-Haber — to get the Lattice Energy in kJ/mol along with its magnitude and relative ionic bond strength.

Crystal structure constant (NaCl: 1.748, CaO: 2.519)

nm

Distance between cation and anion centers

Repulsive force exponent

kJ/mol

Standard enthalpy of formation of the ionic solid

kJ/mol

Enthalpy of sublimation of metal

kJ/mol

Total ionization energy of metal

kJ/mol

Energy to break diatomic nonmetal bonds

kJ/mol

Total electron affinity of nonmetal

Results

Lattice Energy

--

Lattice Energy (Magnitude)

--

Relative Lattice Strength

--

More Chemistry Tools

Frequently Asked Questions

What is lattice energy and why is it important?

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.

What's the difference between Born-Landé equation and Born-Haber cycle methods?

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.

How do I determine the Madelung constant for different crystal structures?

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.

What factors affect the magnitude of lattice energy?

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⁻.

What is the Born exponent and how do I choose its value?

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.

Why might Born-Landé and Born-Haber methods give different results?

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.

What are typical lattice energy values for common compounds?

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.