Enthalpy of Atomisation
The enthalpy change when one mole of gaseous atoms is produced from an element in its standard state.
Formula / equation
ΔH_at°
Unit
kJ/mol
In depth
Atomisation enthalpy is always endothermic because bonds must be broken with none formed. For metals it equals the enthalpy of sublimation and measures metallic bond strength; for diatomic gases it is half the bond dissociation enthalpy. It is a key term in Born–Haber cycles.
Examples in the real world
Sodium requires 107 kJ/mol; tungsten needs 837 kJ/mol, reflecting its very high melting point.