Ionization enthalpy:- It represents the energy required to remove an electron from an isolated gaseous atom (X) with ground state resulting in the formation of a positive ion.
X (g) + Energy → X+ (g) + e-
The ionization enthalpy is expressed in units of kJ mol-1.
Electron gain enthalpy:- When an electron is added to a neutral gaseous atom (X) to convert into a negative ion, the enthalpy change accompanying the process is defined as the electron gain enthalpy.
X (g) + e- → X- (g) ΔH = ΔHeg
