Sometimes there is confusion about the difference between fluorine and fluoride. The element fluorine is a pale, yellow gas found naturally in the Earth’s crust. It is highly reactive, meaning it can combine with nearly any element on Earth.
Fluoride is chemically related to fluorine, but they are not the same. Fluoride is a different chemical compound. Fluoride is created from salts that form when fluorine combines with minerals in soil or rocks. Fluoride is usually very stable and relatively unreactive, unlike its chemical relative fluorine. Any chemical compound that contains the fluoride ion is also known as a fluoride, such as calcium fluoride (CaF2) and sodium fluoride (NaF).