Worksheet: Energies of Atomic Orbitals

In this worksheet, we will practice predicting the effects of shielding, nuclear charge, and orbital occupancy on the relative energies of atomic orbitals.


Which of the following statements is false?

  • AThe energy difference between the 3d and 4s subshells is sometimes less than the pairing energy of the 4s subshell.
  • BElectrons fill subshells of equal 𝑛 in order of increasing 𝑙.
  • CElectrons are usually removed from the 4s subshell before the 3d subshell.
  • DElectrons fill subshells in order of increasing 𝑛.
  • EElectrons are usually added to the 4s subshell before the 3d subshell.


Atoms of Pa, U, Np, Cm, and Lr contain one electron in the 6d subshell and two electrons in the 7s subshell. A 6d0 configuration is produced if the d electron is promoted to a 5f or higher energy orbital. In which of these atoms does changing from a 6d1 to a 6d0 configuration produce the greatest increase in pairing energy?

  • A L r
  • B U
  • C C m
  • D P a
  • E N p


In the experimentally observed 𝑍e values for the 2p elements, we find that the increase in the 𝑍e for a 2p electron is slightly smaller between N and O (Δ𝑍0.62e) than between C and N (Δ𝑍0.69e). Which of the following is not a reason for the differences in the Δ𝑍e values?

  • AThe 𝑍e value for oxygen is raised due to additional shielding from fluorine.
  • BMoving from C to N adds an electron to an unoccupied orbital.
  • CMoving from N to O pairs two electrons in a single orbital.
  • DThe 𝑍e value decreases with an increase in electron repulsion.

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