What is the charge on ions of fluorine (atomic number 9)

A fluorine atom has nine protons and nine electrons, so it is electrically neutral. If a fluorine atom gains an electron, it becomes a fluoride ion with an electric charge of -1.

Ions are formed in order for atoms to gain full valence shells (8 electrons).

That being said, fluorine, with an atomic number of 9, would need to lose one electron in order to have 8 (aka have a full valence shell).

Because it LOSES an electron, it essentially loses a negative charge. This gives it a charge of +1.

Hope this helps! :)