The Born-Haber cycle: what it is and where marks are lost
Dr Lavan Ganeshkumar, PhD · updated 4 October 2026
A Born-Haber cycle is an energy cycle that applies Hess law to an ionic compound. It links the enthalpy of formation of the compound to the enthalpies of atomisation, ionisation, electron affinity and lattice formation.
It is used to find a lattice enthalpy, which cannot be measured directly.
Words that must appear
- Hess law
- Ionic compound
The sign
The cycle contains both endothermic steps (atomisation, ionisation) and exothermic steps (electron affinity, lattice formation). Check the sign of each before adding.
Do not confuse with
Hess law itself. A Born-Haber cycle is an application of it to an ionic compound.
Common questions
What is a Born-Haber cycle?
An energy cycle that applies Hess law to an ionic compound, linking its enthalpy of formation to the steps that build it from gaseous ions.
What is a Born-Haber cycle used for?
To find a lattice enthalpy, which cannot be measured directly.
Which law allows a Born-Haber cycle to be solved?
Hess law.
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