An electron is excited from the n=1 ground state to the n=3 state in a hydrogen atom. Does it take more energy to ionize (completely remove) the electron from n=3 than from the ground state?

1 Answer
Mar 11, 2017

Well, if you are climbing a flight of stairs..........

Explanation:

.........does it take you more energy to climb from the bottom of the stairs, than from 3 steps up the flight of stairs? Quite clearly it does.

When we ionize an electron, essentially we raise it from n=1n=1 to n=oon=; now clearly this is going to be endothermic:

"Atom, (n=1),"+Delta_1 rarr "Atom"^+(n=oo) + e^-

But when we raise the electron from n=1 to n=3, then clearly this also will be endothermic:

"Atom, (n=1),"+Delta_2 rarr "Atom"^+(n=3)+ e^-

"Atom, (n=3),"+Delta_3 rarr "Atom"^+(n=oo) + e^-

Clearly, Delta_2+Delta_3=Delta_1 by considerations of conservation of energy. And thus, necessarily, Delta_1>Delta_3 (and the difference is Delta_2). Are you happy with this treatment?