The difference between fluorine and fluoride is fairly simple. Fluorine is an element and fluoride is the ion of element fluorine. Fluorine is one of the lightest elements among halogens. It is the most electronegative element with a value of 4 on the Pauling scale. Electronegative means the tendency to attract a bonding pair of electrons. Fluoride, on the other hand, is the negative ion of fluorine. Compounds containing the fluoride ion are referred to as fluorides. An example of a fluoride is sodium fluoride (Na+F-).
Fluorine was discovered as an element in other compounds in the early 1500s by the German physician Georgius Agricola. The element was isolated in its pure form by Henri Moissan in late 1800s. Fluorine can bond with almost any element due to its electronegative and oxidizing properties.
When hearing the term fluoride, most of us will generally think of toothpaste. Fuoride is found in nature but the fluoride added to drinking water and toothpaste is synthesized in the lab. In the human body, fluoride reacts with a form of calcium phosphate called hydroxyapatite in the bones and teeth to form fluoroapatite, which also occurs as a mineral. In the right amount, this appears to have a strengthening effect and provides significant protection against tooth decay and dental cavities. Despite its presence in the human body and its beneficial effects at the right levels, fluorine is not considered an essential element as humans appear able to live without it, and too much fluoride can be harmful.
There is some controversy surrounding the use of fluoride in products such as drinking water and toothpaste with the opponents emphasizing the potential harmful effects of excessive fluoride. Opponents of fluoridation of water supplies have argued that it is a form of enforced medication, while those in favor argue that it simply brings fluoride levels up to normal for areas that are deficient in this element.
Although elemental fluorine is highly toxic due to its reactivity, fluorides are generally less so. Nevertheless, ingestion of soluble metal fluorides in other than very small amounts can have serious toxic effects and for this reason, toothpaste and mouthwash should not be swallowed. The acute effects of fluoride ingestion include damage to the brain and kidneys and effects on the heart. The lethal dose for sodium fluoride is estimated at 0.175 – 0.353 ounces (5-10 grams), an amount very unlikely to be absorbed through contact with generally available products containing fluoride. The effects of chronic overexposure to fluoride include mottling of teeth, brittle bones, anemia and stiff joints.
Fluorine and fluoride are widely used in industry. One very useful fluorine-containing product is polytetrafluoroethylene (PTFE), a fluorinated plastic sold under a well-known trade name and used domestically on cooking utensils because of its heat resistance and non-stick properties. In addition, PTFE is used industrially for the storage of reactive substances, due to its chemical inertness. Fluorine and fluoride are also used in the production of pesticides, such as sulfuryl fluoride, and in an intermediate step in the enrichment of uranium for nuclear reactors.