How much energy does it take to ionize a hydrogen atom that is in its first excited state Answer 1 Ionization energy of hydrogen = 13.6 ev.
What is the approximate energy needed
remove the electron from the ground state
the atom. Al string: first excited state (second energy level):
E = -13.6/n^2 = -13.6/2^2 = -3.4 ev.
Thanks to kirchwey for the alert.