The amount of energy required to ionize a hydrogen atom in its ground (or lowest energy) state depends on several factors, including the exact energy level of the electron and the strength of the electric field applied. Generally, it is estimated that approximately 13.6 electron volts (eV) of energy is required to completely ionize a hydrogen atom in its ground (or lowest energy) state. This energy is provided in the form of a photon (high-energy particle of light) of a certain frequency that is able to strip away the lone electron from the atom. In addition, the nuclear force in the hydrogen atom must be overcome to free the electron. This energy is equal to the difference between the binding energy of the electron within the atom and the energy required for the liberated electron to move an infinite distance away from the nucleus. In other words, the total energy required for ionization is the sum of the ionization energy (13.6 eV) and the electron affinity (the energy required for the liberated electron to move an infinite distance away from the nucleus).
