Question

Define ionization enthalpy? What is its unit? What is the principle of its measurement?

Answer 1

Part 1: Ionization enthalpy (I.E.)

Ionization enthalpy is defined as the minimum amount of energy that is required to remove the most loosely bounded electrons that is electron present in the outermost shell from an isolated gaseous atom.

Part 2: Unit of ionization enthalpy

The unit of ionization enthalpy is electron volts $\left(\mathrm{eV}\right)$ per atom or $(\mathrm{kJ}{\mathrm{mol}}^{-1})$.

Part 3: Principle of measurement:

Ionization energy is usually measured in an electric discharge tube in which a fast-moving electron generated by an electric current strikes a gaseous atom of the element, causing it to eject one of its electrons.