Question

the electron configuration for a fluorine ion is... 1s²2s²2p⁶ 1s²2s²2p⁵ 1s² 1s²2s²2p⁶3s²

Explanation:

Fluorine has an atomic number of 9. A fluorine ion ($F^-$) gains one electron. The neutral - fluorine atom has an electron configuration of $1s^{2}2s^{2}2p^{5}$. When it gains an electron, the extra electron goes into the 2p orbital, filling it. So the electron configuration of $F^-$ is $1s^{2}2s^{2}2p^{6}$.

Answer:

$1s^{2}2s^{2}2p^{6}$