Fluoride, represented by the fluoride ion (F-), carries a negative charge of -1. This is because fluorine atoms have seven valence electrons and tend to gain one electron to achieve a stable configuration of eight valence electrons, resulting in a net negative charge. Fluoride ions are highly reactive and readily form ionic bonds with other elements, particularly metals, to create various fluorine-containing compounds. In biological systems, fluoride strengthens tooth enamel and bones by replacing hydroxyl ions in hydroxyapatite crystals.
