What Is Fluoride? Fluoride vs. Fluorine

You can find fluoride in fluoridated toothpaste.
You can find fluoride in fluoridated toothpaste. ipuwadol / Getty Images

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.

Key Takeaways: What Is Fluoride?

  • Fluoride is the name given to the negatively-charged ion of the fluorine atom (F).
  • A fluoride may also be the name of a compound that contains the element.
  • Fluoride is found in toothpaste and public water supplies in some countries. Other countries view fluoride as a toxic compound and seek to remove it from their water.

Fluoride is the negative ion of the element fluorine. The symbol for the element fluorine is F. Fluoride often is written as F-, which stands for the anion of fluorine that has a -1 electrical charge. 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.

Fluorides are found in toothpaste and added to public drinking water in some countries. Water fluoridation usually is accomplished by adding sodium fluoride (NaF), fluorosilicic acid (H2SiF6), or sodium fluorosilicate (Na2SiF6) to drinking water.