Which of the following is the correct electron configuration for the fluoride ion (F⁻)?

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

Answer: (D)

Verified step by step guidance

1. Step 1: Identify the atomic number of fluorine (F). Fluorine has an atomic number of 9, which means a neutral fluorine atom has 9 electrons.
2. Step 2: Understand that the fluoride ion (F⁻) has gained one extra electron compared to the neutral atom, so it has 10 electrons in total.
3. Step 3: Write the electron configuration for 10 electrons by filling the orbitals in order of increasing energy: 1s, 2s, then 2p.
4. Step 4: Recall the maximum number of electrons each subshell can hold: 1s can hold 2, 2s can hold 2, and 2p can hold 6 electrons.
5. Step 5: Combine these to write the full electron configuration for F⁻ as \$1s^{2} 2s^{2} 2p^{6}$, indicating a filled 2p subshell.