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

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

Answer: (B)

Verified step by step guidance

1. Step 1: Identify the atomic number of argon (Ar), which is 18. This means argon has 18 electrons to be arranged in its electron configuration.
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 orbital: 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 all 18 electrons are placed: 1s^2 (2 electrons), 2s^2 (2 electrons), 2p^6 (6 electrons), 3s^2 (2 electrons), and 3p^6 (6 electrons).
5. Step 5: Verify that the total number of electrons adds up to 18 and that the configuration matches the correct full shell structure for argon, which is a noble gas with a complete outer shell.