What is the electron configuration for the fluoride ION?

Answer 1

The fluoride ion is a fluorine atom that has gained 1 electron. So first, let's write the electron configuration of a fluoride atom. F is atomic number 9 and so has 9 electrons.

1s² 2s² 2p⁵. After gaining 1 electron to make the F- ion, the configuration becomes

1s² 2s² 2p⁶ (isoelectronic with Ne)