(A binary compound contains exactly two different elements), that compound then becomes a fluoride, and then named after the fluoride atom (e.g., Bifluoride, HF2-).
Fluorides can be either organic or inorganic compounds which contain the element fluorine. As a halogen, fluorine forms one monovalent bond (-1 charge), with another element.
Different examples of fluorides: Hydrofluoric acid (HF), Sodium Fluoride (NaF) and Calcium Fluoride (CaF2) and Uranium Hexafluoride (UF6).
Note: The Fluorine atom is often written as F-
(The 'F' being for the Fluorine atom, and the 'minus' as the single monolevolent bond)