According to molecular orbital theory, which molecular orbital is the highest occupied molecular orbital (HOMO) in the F⁻ anion?

• A. 3s
• B. 2s
• C. 1s
• D. 2p

Answer: (D)

Verified step by step guidance

1. Recall that molecular orbital (MO) theory describes the combination of atomic orbitals to form molecular orbitals, which are filled with electrons according to their energy levels.
2. Identify the electron configuration of the fluorine atom (F), which has 9 electrons, and then consider the extra electron in the F⁻ anion, making a total of 10 electrons.
3. Determine the order of molecular orbitals for the second period elements (like fluorine) focusing on the valence shell orbitals: 1s, 2s, and 2p orbitals, where 1s is the lowest energy, followed by 2s, and then 2p orbitals.
4. Fill the molecular orbitals with the 10 electrons according to the Aufbau principle, Hund's rule, and Pauli exclusion principle, starting from the lowest energy orbital (1s) up to the highest occupied orbital.
5. Identify the highest occupied molecular orbital (HOMO) as the molecular orbital that contains the last electron added, which for F⁻ is the 2p orbital.