What is ionization enthalpy?

Ionization enthalpy is the enthalpy change when one mole of a gaseous atom loses one electron to form a gaseous cation. Always positive (endothermic).

• Expressed in kJ/mol.
• At school level, used interchangeably with ionization energy.

Factors affecting it: Nuclear charge, atomic radius, shielding effect, orbital type.

Ionization enthalpy is the energy (per mole) required to remove an electron from a gaseous atom always endothermic and always positive.