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.

Q1:

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.

Q2:

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

Q3:

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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