What does fluorine mean?
Fluorine is a chemical element with the atomic number 9 and the symbol F, classified as the lightest of the halogens — the reactive family that also includes chlorine, bromine, and iodine. At ordinary temperatures it is a pale yellow, highly toxic, corrosive gas, and it holds the distinction of being the most electronegative and most reactive element known. It attacks nearly every other element, combining even with noble gases under some conditions, which is why it occurs in nature only in mineral form rather than as a free gas. Fluorine's compounds are industrially important: they appear in toothpaste and drinking-water fluoridation, refrigerants, Teflon, and many pharmaceuticals. The word derives from fluorspar, the mineral calcium fluoride, whose name comes from the Latin fluere, meaning 'to flow', because the mineral was used as a flux in smelting.
nounA highly reactive, pale yellow, poisonous gaseous chemical element with atomic number 9 and symbol F, the lightest member of the halogen group.
- The chemical element of atomic number 9, a pale yellow toxic gas and the most reactive nonmetal.
"Because fluorine is so reactive, it is never found free in nature and must be handled with extreme care."
"Fluorine combines violently with hydrogen at room temperature, sometimes explosively."
"The chemist isolated fluorine only after decades of dangerous experiments that injured several researchers."
As a mass noun denoting a single element, fluorine rarely appears in plural form; plurals are used mainly when referring to multiple atoms or samples of the element in technical writing.
"The sample contained trace amounts of several gases, including minute quantities of fluorines."
Fluorine attacks almost everything it touches — even glass and water — yet a compound of it keeps your teeth healthy every time you brush.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of fluorine
The name fluorine comes from fluorspar (calcium fluoride), the mineral from which the element was first isolated, itself named for the Latin fluere, 'to flow', reflecting its use as a smelting flux. The French physicist André-Marie Ampère suggested the name around 1810–1812, following Humphry Davy's terminology for chlorine. The element was finally isolated in 1886 by Henri Moissan, an achievement recognized with the Nobel Prize in Chemistry in 1906. Related words sharing this Latin root include fluoresce, fluorescent, fluorite, and fluoride.
Related word forms
How fluorine is actually used
Fluorine is a technical term used mainly in chemistry, science education, and industry; in everyday contexts, people more often encounter its compounds (fluorides) than the element itself. Note that British pronunciation commonly places stress on the first syllable (/ˈflɔːraɪn/ or /ˈflʊəriːn/), while American usage may favor /ˈflɔːriːn/.
Easily confused with fluorine
Fluoride refers to the negatively charged ion or a compound containing fluorine (such as in toothpaste), whereas fluorine is the pure chemical element itself.