Which of the following is the ground-state electron configuration of the F⁻ ion?

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

Answer: (C)

Verified step by step guidance

1. Identify the atomic number of fluorine (F), which is 9. This means a neutral fluorine atom has 9 electrons.
2. Recall that the electron configuration of a neutral fluorine atom is \$1s^2 2s^2 2p^5$, corresponding to 9 electrons distributed in the shells.
3. Understand that the F⁻ ion has gained one extra electron compared to the neutral atom, so it has 10 electrons in total.
4. Add the extra electron to the 2p subshell, since it is the next available orbital for electrons in fluorine, resulting in \$1s^2 2s^2 2p^6$.
5. Conclude that the ground-state electron configuration of the F⁻ ion is \$1s^2 2s^2 2p^6$, which corresponds to a full 2p subshell.