Which of the following is the correct electron configuration for argon (Ar)?

• A. 1s^2 2s^2 2p^6 3s^2 3p^6
• B. 1s^2 2s^2 2p^6 3s^2 3p^3
• C. 1s^2 2s^2 2p^6 3s^2 3p^4
• D. 1s^2 2s^2 2p^6 3s^2 3p^5

Answer: (A)

Verified step by step guidance

1. Step 1: Determine the atomic number of argon (Ar), which tells you the total number of electrons. Argon has an atomic number of 18, so it has 18 electrons.
2. Step 2: Recall the order in which electron orbitals are filled according to the Aufbau principle: 1s, 2s, 2p, 3s, 3p, and so on.
3. Step 3: Fill the orbitals with electrons following the maximum capacity of each: 1s can hold 2 electrons, 2s can hold 2, 2p can hold 6, 3s can hold 2, and 3p can hold 6.
4. Step 4: Add the electrons in order until you reach 18 total electrons: 1s^2 (2 electrons), 2s^2 (2 electrons), 2p^6 (6 electrons), 3s^2 (2 electrons), and 3p^6 (6 electrons).
5. Step 5: Write the electron configuration by combining these filled orbitals: \$1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{6}$, which corresponds to the full electron configuration of argon.