What does it look, feel, taste, or smell like?
Fluorine is usually a pale yellow gas. It has a pungent odor. It is far too dangerous to taste or feel.
How was it discovered?
Henri Moissan isolated pure fluorine in 1886. Many other scientists had unsuccessfully tried to isolate fluorine from hydrogen fluoride. In some cases they accidentally killed themselves by exposure to dangerous compounds. Moissan's successful method relied on electrolysis — using an electric voltage to convert fluoride ions to fluorine gas. He won the Nobel Prize in 1906 and died the next year at the age of 54.
Where did its name come from?
Fluorine gets its name from the Latin word fluere, which means "to flow". Fluorspar ores were used as fluxes, which help ores to flow during smelting. Fluorine was later found to be a present in fluorspar.
Where is it found?
Fluorine is so reactive that it is not found in its elemental state. It is always found bonded to a different element. Some common minerals from which fluorine can be extracted include fluoroapatite, cryolite, and hornblende. There are currently no working mines in the US that produce fluoride ores. The last one closed in 1995, so fluorine is imported into the US.
What are its uses?
Fluorine is not used much in the elemental form because it is so reactive. One use is in rocket fuel, where elemental fluorine is used in place of oxygen to help fuels burn.
Fluoride, the ionic form of Fluorine, is put in toothpaste and sometimes in water to help prevent cavities in the teeth.
Teflon, the non stick material found in frying pans, is a polymer that is 75% fluorine by weight. The scientific name for Teflon is polytetrafluoroethene, or PTFE. This is a chain of carbon atoms with two fluorine atoms attached to each carbon atom.
Fluorine is used in hydrofluoric acid in industry. The acid is able to dissolve silicate-containing compounds such as glass and computer chips. Because of this it cannot be stored for a long time in glass containers. The acid is used for cleaning, purification, and etching.
Fluorine can react with uranium to produce uranium hexafluoride. This compound is then centrifuged to separate out the different isotopes of uranium. This is how enriched uranium is obtained.
A major use of fluorine was in the production of CFCs, the chemicals that lead to the ozone hole. These were once common in aerosols and cooling fluids, but have been banned in developed countries in accordance with the Montreal Protocol.
One of the more interesting compounds of fluorine is sulfur hexafluoride, a gas that, unlike most fluorine compounds, is safe to handle. It was long used as a propellant, a gas used to drive others in a spray. Unfortunately it is a strong greenhouse gas and is very limited in its possible uses.
Is it dangerous?
Fluorine gas is extremely poisonous. It can cause chemical burns on the skin. Hydrofluoric acid is very dangerous. It causes burns to the skin like sulfuric acid and other acids do, and is also easily absorbed into the skin. Once inside the body it causes damage to tissues and organs. Exposure of less than 2% of the body to concentrated hydrofluoric acid can be fatal. The small levels of fluoride ions in toothpaste and treated water are not dangerous, although slightly higher levels can cause unsightly (and permanent) mottling of the teeth.