The potential energy is taken to be zero for an electron at an infinite distance 4rm d nucleus.?

Question

The potential energy is taken to be zero for an electron at an infinite distance 4rm d nucleus.
n=4 ---------------------------- -2eV
n=3 ---------------------------- -5eV

n=2 ----------------------------- -10eV


n=1 ------------------------------ -20eV

Part A -
How much energy (in eV) does it take to ionize an electron from the ground level?
Part B -
An 18.0 eV photon is absorbed by a searsium atom in its ground level. As the atom returns to its ground level, what possible energies can the emitted photons have? Assume that there can be transitions between all pairs of levels.
Part C -
What will happen if a photon with an energy of 8.00eV} strikes a searsium atom in its ground level? Why?
Part D -
Photons emitted in the searsium transitions n=3→n=2 and n=3→ n=1 will eject photoelectrons from an unknown metal, but the photon emitted from the transition {n=4 →n= 3} will not. What are d limits (max and min possible values) of d work function of d metal.
Ǿ_min & Ǿ_max=

Answer 1

Part a electron needs 20 eV since the ground state is -20 eV. That would take the electron to 0 eV potential energy, hence ionizing the atom.

Part b. I assume the energy diagram above is the searsium atom. Then the ground state electron goes from
n =1 -20 eV + 18 eV --> n=4 -2 eV

transistions
n= 4 --> n = 3 3eV
n = 3 -.> n= 2 5 eV
n = 2 --> n =1 10 eV
Total 18 eV

n=4 --> n =1 18 eV

n = 4 --> n=2 8 ev
n=2 --> n=1 10 ev
Total 18 ev

Part c. Photon scatters off the atmo since it does not have enough energy to be absorbed by a ground state electron.

part d. n=3 - n=2 gives up 5 ev, n = 3 - n=1 gives up 15 ev while n=4 to n=3 gives up 3 eV. So min work function is at most 5 eV since that is when photoelectric effect is observed, and max work function is at least 15 eV since photoelectric effect is observed at this energy.

Answer 2

do your own homework