Fluorine (noun)

A chemical element with the symbol F and atomic number 9. It is the lightest halogen and is a reactive, pale yellow, gaseous element.

Origin:

Early 19th century: from french fluorine, from fluorer 'to fluoridate', from latin fluere 'to flow', from fluvius 'a river' (because of its occurrence in the mineral fluorspar).

Examples:

1. Fluorine is used in the production of uranium fuel for nuclear power plants.
2. Fluorine is important in the production of fluorocarbons, which are used as refrigerants and solvents.
3. Fluorine is added to water to help prevent tooth decay and promote oral health.
4. Fluorine is a highly reactive element that readily forms compounds with other elements.
5. Fluorine is the 13th most abundant element in the earth's crust, but is never found in nature as a free element.