What Is Fluoride?

You can find fluoride in fluoridated toothpaste.
You can find fluoride in fluoridated toothpaste. Adam Ciesielski, stock.xchng

Are you confused about the difference between fluoride and fluorine or simply want to know what fluoride is? Here's the answer to this common chemistry question.

Fluoride is the negative ion of the element fluorine. Fluoride often is written as F-. Any compound, whether it is organic or inorganic, that contains the fluoride ion is also known as a fluoride. Examples include CaF2 (calcium fluoride) and NaF (sodium fluoride). Ions containing the fluoride ion are similarly called fluorides (e.g., bifluoride, HF2).

To summarize: fluorine is an element; fluoride is an ion or a compound which contains the fluoride ion.

Water fluoridation usually is accomplished by adding sodium fluoride (NaF), fluorosilicic acid (H2SiF6), or sodium fluorosilicate (Na2SiF6) to drinking water.