What is the ground-state electron configuration of magnesium (Mg)?

• A. $1s^{2}2s^{2}2p^{6}3p^2$
• B. $1s^{2}2s^{2}2p^{5}3s^2$
• C. $1s^{2}2s^{2}2p^{6}3s^1$
• D. $1s^{2}2s^{2}2p^{6}3s^2$

Answer: (D)

Verified step by step guidance

1. Step 1: Identify the atomic number of magnesium (Mg). Magnesium has an atomic number of 12, which means it has 12 electrons in its neutral state.
2. Step 2: Recall the order in which electron orbitals are filled according to the Aufbau principle. The filling order is: 1s, 2s, 2p, 3s, 3p, and so on.
3. Step 3: Distribute the 12 electrons into the orbitals following the filling order and the maximum number of electrons each orbital can hold: 1s can hold 2, 2s can hold 2, 2p can hold 6, and 3s can hold 2.
4. Step 4: Write the electron configuration by listing the orbitals and the number of electrons in each, using the format \(n\text{s}^{x}\) or \(n\text{p}^{y}\), where \(n\) is the principal quantum number and \(x\), \(y\) are the number of electrons in those orbitals.
5. Step 5: Verify that the total number of electrons in your configuration adds up to 12 and that the configuration follows the Aufbau principle, Hund's rule, and the Pauli exclusion principle.