How to Calculate Lattice Energy
What is Lattice Energy?
Lattice energy is the energy released when gaseous ions combine to form a crystalline ionic solid (or equivalently, the energy required to separate the solid into gaseous ions). It measures the strength of ionic bonding.
Step-by-Step Guide
- 1Proportional to |z+||z−|/r (Coulomb's law)
- 2|z| = ionic charges · r = sum of ionic radii
- 3Higher charges and smaller ions → larger lattice energy
- 4Measured experimentally via Born-Haber cycle
Worked Examples
Input
NaCl vs MgO comparison
Result
NaCl ≈ −787 kJ/mol · MgO ≈ −3795 kJ/mol
MgO has 2+ and 2− ions → much larger lattice energy
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