If a hydrogen atom in the ground state absorbs a 20.0 eV photon, what kinetic energy of the electron results?
A) this cannot happen
B) 20.0 eV
C) 13.6 eV
D) 6.4 eV
E) 33.6 eV

Question

Quizplus · Accepted Answer

When a hydrogen atom absorbs a photon, the electron can jump to a higher energy level. The energy of the photon must be equal to the energy difference between the initial and final energy levels of the electron.

In this case, the hydrogen atom is in the ground state, which is its lowest energy level. The energy of the ground state is -13.6 eV. If it absorbs a photon with 20.0 eV of energy, the electron jumps to a higher energy level. The first excited state has an energy of -3.4 eV.

So the energy absorbed by the atom is 20.0 eV, but the energy of the electron in the first excited state is only -3.4 eV. That means the electron had to lose 16.6 eV of energy in the jump. That lost energy becomes the electron's kinetic energy.

So the kinetic energy of the electron is 16.6 eV. This is choice D.

If a Hydrogen Atom in the Ground State Absorbs a 20.0