Thermodynamics: Enthalpy Definitions

Enthalpy of formation: defines the heat exchanged or absorbed during the formation of one mole of a compound from its elements in their standard states.
Ionisation enthalpy: represents the energy required to remove one mole of electrons from one mole of gaseous atoms or ions.
Atomisation enthalpy: measures the energy needed to convert one mole of an element in its standard state into its constituent atoms in the gas phase.
Electron affinity: quantifies the energy change that occurs when one mole of electrons combines with one mole of gaseous atoms or ions to form one mole of gaseous ions with a single negative charge.
Bond enthalpies: measures the energy required to break one mole of a specific type of bond in a molecule or compound.