Which of the following is the correct orbital diagram for the ground state of carbon (atomic number 6)?

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

Answer: (D)

Verified step by step guidance

1. Step 1: Determine the total number of electrons in a neutral carbon atom. Since carbon has an atomic number of 6, it has 6 electrons.
2. Step 2: Recall the order of orbital filling according to the Aufbau principle: electrons fill orbitals starting from the lowest energy level to higher ones. The order for carbon is 1s, 2s, then 2p orbitals.
3. Step 3: Fill the 1s orbital first with 2 electrons, represented as paired spins (↑↓), because it is the lowest energy orbital.
4. Step 4: Next, fill the 2s orbital with 2 electrons, also paired (↑↓), since it is the next lowest energy orbital.
5. Step 5: Finally, place the remaining 2 electrons in the 2p orbitals. According to Hund's rule, electrons occupy degenerate orbitals singly with parallel spins before pairing up. Therefore, place one electron in each of two separate 2p orbitals with parallel spins (↑ ↑).