Here's how to determine the electron configuration of the fluorine ion (F⁻):

1. Neutral Fluorine (F)

* Fluorine has an atomic number of 9, meaning it has 9 protons and 9 electrons.

* The electron configuration for neutral fluorine is: 1s² 2s² 2p⁵

2. Fluorine Ion (F⁻)

* Fluorine gains one electron to achieve a stable octet (8 electrons in its outer shell).

* This adds one electron to the 2p subshell.

* The electron configuration for the fluoride ion (F⁻) becomes: 1s² 2s² 2p⁶