An electron of know KE collides with a hydrogen atom in its ground state. With what possible KE may it rebound?
KE = 11.5 eV
2. The attempt at a solution
I assumed that the electron may either hit an orbiting electron and excite him (maximum layer is n = 2, change in KE = 11.5 - (13.6 - 3.4) = 1.3 eV)
or miss it (KE unaltered = 11.5eV)
Those answers are correct, yet I don't understand them fully.
3. Relevant questions
How do we know that the orbiting electron will take the maximum amount of energy it can take? Is it a simplification or a free electron has to give this amount of energy to the orbiting electron? Why?
Also, can we speak of 'rebounding off the atom' if the electron doesn't hit the free electron? It cannot collide with atom's nucleus as it's energy is unaltered, so how may it rebound?