L

Lattice Energy

U = −Mz₊z₋e²Nₐ/(4πε₀r₀)(1−1/n); Born-Landé equation
Quick Reference
Formula / NotationU = −Mz₊z₋e²Nₐ/(4πε₀r₀)(1−1/n); Born-Landé equation
Also Known AsLattice dissociation energy, U_L, ionic lattice energy, Madelung energy

What is Lattice Energy?

The energy released when gaseous ions combine to form a solid ionic lattice, or equivalently, the energy required to separate one mole of ionic solid into its constituent gaseous ions. Larger magnitude lattice energies indicate more stable ionic compounds. Calculated via Born-Haber cycle.

Formula & Notation

U = −Mz₊z₋e²Nₐ/(4πε₀r₀)(1−1/n); Born-Landé equation

Other Names / Synonyms: Lattice dissociation energy, U_L, ionic lattice energy, Madelung energy

Properties & Characteristics

Lattice energy (U or ΔH_L) is the energy required to completely separate one mole of an ionic crystal lattice into gaseous ions at infinite separation, or equivalently (negative of) the energy released on forming the lattice from gaseous ions. It is always endothermic when defined as lattice dissociation (U > 0). Lattice energy increases with higher ionic charges and smaller ionic radii. It is calculated by the Born-Landé or Kapustinskii equation, or indirectly via Born-Haber cycles.

Uses & Applications

Lattice energy determines ionic compound properties: hardness, melting point, solubility (balance of lattice energy vs. hydration energy), and thermal stability. High lattice energy (MgO: ~3850 kJ/mol) gives high melting point refractory material; low lattice energy (CsI: ~600 kJ/mol) gives low melting point and higher solubility.

Safety Information

No direct safety concern. Compounds with very high lattice energy (oxides, fluorides of small highly charged ions) are chemically resistant but require very high temperatures for processing. Compounds with very low lattice energy (some metal iodides, perchlorates) dissolve readily, potentially releasing toxic ions.

Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.

Key Facts

Term Lattice Energy
Formula U = −Mz₊z₋e²Nₐ/(4πε₀r₀)(1−1/n); Born-Landé equation
Synonyms Lattice dissociation energy, U_L, ionic lattice energy, Madelung energy

Frequently Asked Questions

The energy released when gaseous ions combine to form a solid ionic lattice, or equivalently, the energy required to separate one mole of ionic solid into its constituent gaseous ions. Larger magnitude lattice energies indicate more stable ionic compounds. Calculated via Born-Haber cycle.

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