Intermediate Topic 142 of 1102 Bonding & Molecular Structure
Lattice Energy
The energy released when gaseous ions form one mole of ionic solid.
Practise Bonding & Molecular Structure All Bonding & Molecular Structure topics
In-depth explanation of Lattice Energy
Lattice energy is the energy released when one mole of an ionic solid forms from its gaseous ions. Its magnitude reflects the strength of ionic bonding throughout the crystal. In the simple electrostatic model, lattice energy is proportional to the product of the ion charges divided by the sum of the ion radii, so it rises steeply with higher charges and smaller ions. Lattice energy largely determines melting point, hardness and how readily a salt dissolves, since dissolving requires overcoming it. It cannot be measured directly and is usually derived indirectly.
Going deeper: Lattice Energy
Key ideas: Use the Born-Lande type scaling: U proportional to z+ times z- divided by (r+ plus r-). Example: MgO uses charges 2 and 2 with small radii, so it is about 4 times larger than NaCl type with charge 1 and 1 and comparable size. Compare compounds by charge first, then radius. Typical values range from 600 to above 4000 kJ/mol.
Common mistakes and connections: Common errors include confusing lattice energy defined as formation from gaseous ions with the reverse process, which has the same magnitude but opposite sign, and comparing only radii when charges differ. Also lattice energy alone does not decide solubility, hydration enthalpy matters too. Connects to Born-Haber cycles, melting point, hardness and solubility.
Visualization of Lattice Energy
Magnitude of lattice energy: doubly charged ions in MgO and CaO give values four to five times larger than singly charged NaCl and KCl. The interactive lesson shows this as a live animation or chart.
Worked example and use case
Magnesium oxide, with doubly charged ions, has a lattice energy of about 3850 kJ/mol, far larger than the 787 kJ/mol of sodium chloride.
Frequently asked questions about Lattice Energy
What is Lattice Energy?
The energy released when gaseous ions form one mole of ionic solid.
Is Lattice Energy a beginner, intermediate or advanced topic?
Lattice Energy is a intermediate topic in Bonding & Molecular Structure. It builds on the vocabulary of beginner topics in this area.
What should I learn before Lattice Energy?
Study these earlier topics in Bonding & Molecular Structure first: Percent Ionic Character, Fajans' Rules, Polarizability.
What comes after Lattice Energy?
The next topics in Bonding & Molecular Structure are Born-Haber Cycle and Properties of Ionic Compounds.
Can I practise Lattice Energy with quizzes?
Yes. The interactive lesson includes a self-check question on Lattice Energy, and the Bonding & Molecular Structure quiz draws on every topic in this area.
Where Lattice Energy fits in Bonding & Molecular Structure
Lattice Energy is topic 27 of 104 in Bonding & Molecular Structure.