Facts about fluoride

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The most reactive element on the Periodic Table, fluorine has a strong story in its quest for discovery. Despite the difficult and sometimes explosive properties of fluoride, it is a vital element for humans and animals, which is why it usually is in drinking water and toothpaste.

Just the facts

  • Atomic number (number of protons in the nucleus): 9
  • The atomic symbol (on the Periodic Table of the Elements): F
  • Atomic weight (average atomic mass): 18.998
  • Density: 0.001696 grams per cubic centimeter
  • Phase at room temperature: Gas
  • Melting point: minus 363.32 degrees Fahrenheit (minus 219.62 degrees Celsius)
  • The boiling point: minus 306.62 degrees Fahrenheit (minus 188.12 degrees Celsius)
  • The number of isotopes (atoms of the same element with a different number of neutrons): 18
  • The most common isotopes: F-19 (100% natural abundance)

History

Early chemists have been trying for years to isolate the element from various fluoride compounds. However, fluorine does not occur free in nature, and no chemical substance is capable of releasing fluoride from either of its complexes because of its reactive nature.

For many centuries, mineral fluorite was used in metal cleaning. Known today as calcium fluoride (CaF2), it was used as a secretion to separate pure metal from undesirable minerals in the ore, according to Chemicool. “Fluorite” comes from the Latin word “fluere”, meaning “leak”, because that’s what fluorite allowed metals to do. The mineral was also called a Bohemian emerald and was used in glass corrosion, according to the Jefferson Laboratory.

Many scientists for decades tried to experiment with fluorite to better study its properties, as well as its composition. In their experiments, chemists often produced fluoric acid (now known as hydrofluoric acid, HALF), an incredibly reactive and dangerous acid. Even small spikes of this acid on the skin can be fatal, according to Chemicool. Several scientists were wounded, blinded or killed in some experiments.

In the early 19th century, scientists Andre-Marie Amper, in France, and Humphry Davy, in England, corresponded about the possibility of a new element in acid. In 1813, Davy announced the discovery of a new element and called it the fluorine of Ampere’s proposal.

Henri Moissan, a French chemist, finally allocated fluoride in 1886 – after being poisoned several times in his pursuit. He was awarded the Nobel Prize in 1906 for the fluorine insulation by electrolysis of a dry fluoride compound of potassium hydrogen (KHF2) and dry hydrofluoric acid.

Use of fluorine

For many years, fluoride salts or fluoride compounds have been used in welding and for glass coating, according to the Royal Society. For example, hydrofluoric acid is used to grow a glass of light bulbs.

Fluorine is a vital element in the nuclear industry, according to the Royal Society. It is used to make uranium hexafluoride, which is necessary to separate uranium isotopes. Sulfur hexafluoride is a gas used to insulate powerful electrical transformers.

Chlorofluorocarbons (CFCs) were once used in aerosols, refrigerators, air conditioners, foam food packaging and fire extinguishers. That use has been banned since 1996, because they contribute to the thinning of the ozone layer, according to the National Institutes of Health. Prior to 2009, CFCs were used in inhalers to control asthma, but those types of inhalers were gradually reduced in 2013.

Fluoride is used in many fluorochemicals, including solvents and high-temperature plastics such as Teflon (poly (tetrafluoroethene), PTFE). Teflon is known for its non-sticking properties and is used in frying pans. It is also used for cable insulation for plumber tape and as a Gore-Tex® base (used in waterproof shoes and clothing).

Fluoride is added to the supply of tap water at a proportion of about one part per million to help prevent tooth decay, according to Jefferson Lab. Several fluoride complexes are added to the toothpaste, also to help prevent tooth decay.

Health and environmental effects of fluoride

Although all humans and animals are subjected to and need small amounts of fluoride, an element in any that a sufficiently large dose is extremely toxic and dangerous. According to Lenntech, fluoride can naturally be found in water, air and both plant and animal based foods in small amounts. Large amounts of fluoride are found in several foods, such as tea and shellfish.

While small amounts of fluoride are important for maintaining the strength of our bones and teeth, too much can have the opposite effect of causing osteoporosis or tooth decay, and also potentially damaging the kidneys, nerves and muscles.

In its gaseous form, fluoride is incredibly dangerous. Small amounts of fluoride gas can surround irritation of the eyes and nose, while large amounts can be fatal, according to Lenntech. Hydrofluoric acid, as another example, can also turn out to be fatal, when even a small spike in the skin occurs, according to Chemicool.

In the fluorine environment, the 13th most abundant element in the earth’s crust is usually grounded in the soil and readily combines with soil, rock, coal and clay, according to Lenntech. Plants can absorb fluoride from the soil, although high concentrations can lead to damage. Corn and apricots, for example, among plants that are the most susceptible to damage and shrinking growth when subjected to elevated levels of fluoride.

Who knew?

  • Because fluorine is the most chemically reactive element, it must be handled with great care, as it can sometimes explode on contact with all other elements, excluding oxygen, helium, neon and krypton, according to Chemicool.
  • Steel wool lights up when exposed to fluoride, according to the Royal Society of Chemistry.
  • Fluorine is also the most electronegative element. Fluorine attracts electrons more readily than any other element.
  • On average, the amount of fluoride in the human body is three milligrams.
  • Fluoride, first of all, is mined in China, Mongolia, Russia, Mexico and South Africa, according to the Education Coalition of Minerals.
  • Fluoride is created in sun-like stars by the end of their life, in accordance with the article 2014, published in Astrophysical Letters on the Journal. The element is formed under higher pressures and temperatures in the star, when it expands to become a red giant. When the outer layers of the star are advanced, far creating a planetary nebula, fluorine travels along with other gases into the interstellar medium, ultimately forming new stars and planets.
  • According to the Journal of Chemistry, approximately 25 percent of drugs and medications, including those for cancer, the central nervous system and the cardiovascular system, contain some form of fluoride.

Current research

Although fluoride can be toxic when the concentration in the body is too high, it can also be a useful element to include in cancer cures, according to the 2018 article published in the Journal of Fluorine Chemistry. According to the study, replacing the compounds of carbon hydrogen or carbon oxygen with a carbon fluoride compound in the active drug components usually indicates that improving the effectiveness of the drugs, including higher metabolic stability, increased binding to target molecules and increased membrane patency. It is hoped that with the increased efficacy of drugs, along with tumor-specific targeted drugs or targeted drug delivery systems, the quality of life of cancer patients can be significantly improved by traditional methods, such as chemotherapy, in which cancer cells, as well as healthy cells, are targeted preparations.

This new generation of cancer-fighting drugs, as well as fluoride studies to deliver drugs, has been tested against cancer stem cells and has shown promise in the planning and control of cancer stem cells, according to the study. The researchers found that drugs that included fluorine were several times more active against various cancer stem cells and showed better stability than traditional cancer-fighting drugs.