What is Ionization Enthalpy

Answer: Ionization enthalpy is defined as the energy needed for removing an electron from a gaseous atom that is isolated in nature from its ground state. Ionization enthalpy is expressed in the form of KJ mol^-1 and is denoted by Δ_iH. Quantitative measurement is defined as the measurement of an atom to lose an electron. A certain amount of energy is always needed for removing an electron from within an atom. Hence Ionization enthalpy is always taken as positive.