Lattice Energy Calculator

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Kapustinskii only needs ionic radii and charges. Born-Lande needs the Madelung constant and closest-approach distance. Born-Haber uses experimental enthalpies.
Select a common cation or choose Custom to enter your own radius and charge.
Crystal-ionic radius of the cation in picometres.
pm
Absolute value of the cation charge (e.g. 2 for Mg2+).
Select a common anion or choose Custom to enter your own radius and charge.
Crystal-ionic radius of the anion in picometres.
pm
Absolute value of the anion charge (e.g. 2 for O2-).
Total number of ions in one formula unit (v). NaCl = 2, CaF2 = 3, Al2O3 = 5.
Lattice energyModerate lattice energy
745.9kJ/mol

Energy released when gaseous ions condense into the crystalline lattice

MethodKapustinskii approximation
Interionic distance (r0)283pm
Charge product |z+||z-|1
745.9 kJ/mol
Low<600Moderate600-1500High1500-3000Very high3000+

Lattice energy: 745.9 kJ/mol (Kapustinskii approximation).

  • The moderate lattice energy is typical of alkali-metal halides such as NaCl (787 kJ/mol) and KCl (717 kJ/mol). These compounds are stable but readily soluble in water.
  • The interionic distance of 283 pm is inversely proportional to lattice energy: smaller ions pack closer, increasing electrostatic attraction.

Next stepFor a more precise value, switch to the Born-Lande method with the known Madelung constant and shortest interionic distance from X-ray crystallography.

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