Which of the following represents the ground state electron configuration of selenium (Se)?

• A. 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^4
• B. 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^2
• C. 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^6
• D. 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^8 4p^6

Answer: (A)

Verified step by step guidance

1. Step 1: Determine the atomic number of selenium (Se). Selenium has an atomic number of 34, which means it has 34 electrons in its neutral ground state.
2. Step 2: Recall the order of filling electron orbitals according to the Aufbau principle, which is: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, and so on.
3. Step 3: Begin filling the orbitals with electrons following the order and the maximum number of electrons each orbital can hold: s orbitals hold 2 electrons, p orbitals hold 6, and d orbitals hold 10.
4. Step 4: Fill the orbitals up to 34 electrons: 1s^2 (2 electrons), 2s^2 (2 electrons), 2p^6 (6 electrons), 3s^2 (2 electrons), 3p^6 (6 electrons), 4s^2 (2 electrons), 3d^{10} (10 electrons), and then place the remaining electrons in the 4p orbital.
5. Step 5: Calculate how many electrons remain for the 4p orbital after filling the previous orbitals, and write the final electron configuration accordingly.