The energy levels of a single-electron atom (or the approximation ...

[saliriagwu]

The energy levels of a single-electron atom (or the approximation for one electron outside of a filled shell) can be split due to a relationship between the spin and the orbital angular momentum. Choose the statement that best explains why this occurs.
  a.The electron is affected by the magnetic field of the proton, which in the rest frame of the electron is seen as orbiting the electron.
  b.There is a state with lesser energy when the spin magnetic moment of the electron and internal magnetic field of the atom are aligned.
  c.Only in an external magnetic field do the energy levels split due to spin-orbit coupling.
  d.Only in an external electric field do the energy levels split due to spin-orbit coupling.
  e.The total angular momentum component in the z-direction is not quantized and can take on any value as a sum of orbital and spin angular momentum.

Question 2

Although it seems intuitive that electrons in atoms should fill the 1s shell, 2s shell, 2p shell, 3s shell and so on in order of principal quantum number and orbital angular momentum quantum number, this is not the case. For instance, the 4s subshell fills before the 3d subshell. Which of the following statements does NOT help explain why this occurs?
 

a.Electrons fill the lowest energy levels available to them.
  b.Subshells with low l values have more elliptical orbits, spend more time inside the filled shells, and are at lower energies.
  c.Subshells with higher l values spend less time inside the filled shells and have higher energies.
  d. Electrons fill subshells by order of the subshells with least total electrons first, then subshells with greater number of total electrons.
  e.Electrons in shells with higher energy generally experience less shielding of nuclear charge.

[mjbamaung]

Answer to Question 1

a.
If viewed from the rest frame of the electron, the proton appears to be orbiting the electron. The moving charge creates a magnetic field, and the spin magnetic moment of the electron can either align or antialign ( ) with this to produce a split in the energy of the particular nl subshell.

Answer to Question 2

e.
This statement is not true. The subshells at higher energies usually have more shielding from nuclear charge. They spend less time inside the filled shells because their orbits are less elliptical and therefore they lie at higher energies.

[saliriagwu]

Gracias!

[bbburns21]

Great answer, keep it coming