Which of the following electron orbital diagrams represents a violation of the aufbau principle?

• A. 1s: ↑↓ 2s: ↑↓ 2p: ↑ 2p: ↑ 2p: ↑
• B. 1s: ↑↓ 2s: ↑↓ 2p: ↑↓ 2p: ↑↓ 2p: ↑↓
• C. 1s: ↑↓ 2s: ↑↓ 2p: ↑ 3s: ↑
• D. 1s: ↑↓ 2s: ↑↓ 2p: ↑↓ 2p: ↑ 2p: ↑

Answer: (C)

Verified step by step guidance

1. Recall the Aufbau principle, which states that electrons fill atomic orbitals starting from the lowest energy level to higher energy levels in a specific order.
2. Identify the order of orbital filling: 1s, 2s, 2p, 3s, and so on, where all orbitals in a lower energy level must be fully occupied before electrons occupy orbitals in a higher energy level.
3. Examine each electron configuration given and check if any electron occupies a higher energy orbital before all lower energy orbitals are completely filled.
4. Focus on the configuration where an electron is placed in the 3s orbital while the 2p orbitals are not fully occupied, which violates the Aufbau principle because 2p orbitals should be filled before moving to 3s.
5. Conclude that the diagram with electrons in 1s, 2s, partially filled 2p, and then an electron in 3s represents a violation of the Aufbau principle.