Which of the following is the correct ground-state electron configuration for an atom of polonium (atomic number 84)?

• A. Rn 6p4
• B. Rn 6d10 7s2
• C. Xe 4f14 5d10 6s2 6p4
• D. Rn 7s2 5f14

Answer: (A)

Verified step by step guidance

1. Identify the atomic number of polonium, which is 84. This tells us the total number of electrons in a neutral polonium atom.
2. Recall that the ground-state electron configuration is built by filling orbitals in order of increasing energy, following the Aufbau principle, Pauli exclusion principle, and Hund's rule.
3. Start from the nearest noble gas preceding polonium to simplify the configuration. The noble gas before polonium is radon (Rn), with atomic number 86, but since polonium has 84 electrons, we consider the electron configuration up to radon minus two electrons.
4. Add the electrons beyond the noble gas core by filling the 6p orbitals, since polonium is in group 16 and period 6, which means its valence electrons occupy the 6p subshell.
5. Write the full electron configuration by combining the noble gas core (Rn) with the valence electrons in the 6p subshell, resulting in \(\mathrm{Rn}\ 6p^4\).