Fluoride--What it is.

Fluoride is compound containing fluorine and another element. Fluorine is a very reactive (non-stabile) element. Fluorine combines readily with nearly all the other elements. This is due to it having only seven electrons in its outer shell. The element fluorine is represented by the symbol “F”. It has an atomic weight of 18.9 and an atomic number of 9. Fluoride is an anion of fluorine (F-) and most compounds that contain F- are called fluorides.

Diagram Group, Chemistry handbook, Revised edition, Facts on File, New York, 2006