Question

How much energy is required to take an electron in this atom from the ground state to the first excited state

Answer 1

The second energy level is -3.4 eV. Thus it would take E2 − E1 = -3.4 eV − -13.6 eV = 10.2 eV to excite the electron from the ground state to the first excited state. If a photon has more energy than the binding energy of the electron then the photon will free the electron from the atom – ionizing it.