What is the ground-state electron configuration for krypton (Kr)?

• A. $[Ar]4^{s}23^{d}104^{p}5$
• B. $[Ne]3^{s}23^{p}64^{s}23^{d}104^{p}6$
• C. $[Ar]4^{s}24^{p}63^{d}10$
• D. $[Ar]4^{s}23^{d}104^{p}6$

Answer: (D)

Verified step by step guidance

1. Identify the atomic number of krypton (Kr), which is 36. This tells us krypton has 36 electrons to arrange in its ground-state electron configuration.
2. Recall the order in which electron orbitals are filled according to the Aufbau principle: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, and so on.
3. Use the noble gas shorthand notation to simplify the configuration. The noble gas preceding krypton is argon (Ar), which accounts for the first 18 electrons. So start with \([\mathrm{Ar}]\).
4. Add the electrons beyond argon by filling the 4s orbital with 2 electrons, then the 3d orbital with 10 electrons, and finally the 4p orbital with 6 electrons to reach a total of 36 electrons.
5. Write the full ground-state electron configuration for krypton as \([\mathrm{Ar}]\,4s^{2}\,3d^{10}\,4p^{6}\), which reflects the complete filling of these orbitals.