10 Interesting Fluorine Facts

Fluorine (F) is an element you encounter daily, most often as fluoride in water and toothpaste. Here are 10 interesting facts about this important element. You can get more detailed information about chemical and physical properties on the fluorine facts page.

1. Fluorine is the most reactive and most electronegative of all the chemical elements. The only elements it doesn't vigorously react with are oxygen, helium, neon, and argon. It is one of the few elements that will form compounds with noble gases xenon, krypton, and radon.
2. Fluorine is the lightest halogen, with atomic number 9. Its standard atomic weight is 18.9984 and is based on its single natural isotope, fluorine-19.
3. George Gore managed to isolate fluorine using an electrolytic process in 1869, but the experiment ended in disaster when fluorine reacted explosively with hydrogen gas. Henri Moisson was awarded the 1906 Nobel Memorial Prize in Chemistry for isolating fluorine in 1886. He also used electrolysis to obtain the element but kept the fluorine gas separate from the hydrogen gas. Although he was the first to successfully obtain pure fluorine, Moisson's work was interrupted multiple times when he was poisoned by the reactive element. Moisson was also the first person to make artificial diamonds, by compressing charcoal.
4. The 13th most abundant element in the Earth's crust is fluorine. It is so reactive that it is not found naturally in pure form but only in compounds. The element is found in minerals, including fluorite, topaz, and feldspar.
5. Fluorine has many uses. It is found as fluoride in toothpaste and drinking water, in Teflon (polytetrafluoroethylene), drugs including the chemotherapeutic drug 5-fluorouracil, and etchant hydrofluoric acid. It is used in refrigerants (chlorofluorocarbons or CFCs), propellants, and for the enrichment of uranium by UF₆ gas. Fluorine is not an essential element in human or animal nutrition. Topical fluoride application, as from toothpaste or mouthwash, was once believed to be effective for the conversion of tooth enamel hydroxyapatite into stronger fluorapatite, but more recent studies indicate fluoride aids enamel regrowth. Trace dietary fluorine levels may impact bone strength. While fluorine compounds are not found in animals, there are natural organofluorines in plants, which typically act as defenses against herbivores.
6. Because it is so reactive, fluorine is difficult to store. Hydrofluoric acid (HF), for example, is so corrosive it will dissolve glass. Even so, HF is safer and easier to transport and handle than pure fluorine. Hydrogen fluoride is considered to be a weak acid at low concentrations, but it acts as a strong acid at high concentrations.
7. Although fluorine is relatively common on Earth, it is rare in the universe, believed to be found at concentrations of about 400 parts per billion. While fluorine forms in stars, nuclear fusion with hydrogen produces helium and oxygen, or fusion with helium makes neon and hydrogen.
8. Fluorine is one of the few elements that can attack diamond.
9. The pure non-metallic element is a gas at room temperature and pressure. Fluorine changes from an extremely pale yellow diatomic gas (F₂) into a bright yellow liquid at -188 degrees Celsius (-307 Fahrenheit). Fluorine resembles another halogen, chlorine. The solid has two allotropes. The alpha form is soft and transparent, while the beta form is hard and opaque. Fluorine has a characteristic pungent odor that can be smelled at a concentration as low as 20 parts per billion.
10. There is only one stable isotope of fluorine, F-19. Fluorine-19 is highly sensitive to magnetic fields, so it is used in magnetic resonance imaging. Another 17 radioisotopes of fluorine have been synthesized, ranging in mass number from 14 to 31. The most stable is fluorine-17, which has a half-life just of under 110 minutes. Two metastable isomers are also known. The isomer ^18mF has a half-life of about 1600 nanoseconds, while ^26mF has a half-life of 2.2 milliseconds.

Sources

• Banks, R. E. (1986). "Isolation of Fluorine by Moissan: Setting the Scene." Journal of Fluorine Chemistry. 33 (1–4): 3–26.
• Bégué, Jean-Pierre; Bonnet-Delpon, Danièle (2008). Bioorganic and Medicinal Chemistry of Fluorine. Hoboken: John Wiley & Sons. ISBN 978-0-470-27830-7.
• Lide, David R. (2004). Handbook of Chemistry and Physics (84th ed.). Boca Raton: CRC Press. ISBN 0-8493-0566-7.