# Question #3e3ea

Nov 29, 2015

It will become isoelectronic to the noble gas neon.

#### Explanation:

The atomic number of fluorine is 9. Therefore fluorine atoms have 9 positively charged protons in their atomic nuclei. Neutral fluorine atoms will also have 9 negatively charged electrons in their electron clouds.

The electron configuration of a neutral fluorine atom is $\text{1s"^2"2s"^2"2p"^5}$.

When a fluorine atom gains one electron, it becomes a fluoride ion with 10 negatively charged electrons and 9 positively charged protons, which gives it a ${1}^{-}$ charge.

The electron configuration of a $\text{F"^(-)}$ ion is $\text{1s"^2"2s"^2"2p"^6}$.

This is the same electron configuration as neon, which has atomic number 10, so it has 10 protons and 10 electrons in its neutral atoms.

The electron configuration of neon is $\text{1s"^2"2s"^2"2p"^6}$.