(Symbol : F; Atomic no. 9 ) is a yellowish, poisonous, corrosive gas under
ordinary conditions. Fluorine becomes a yellow liquid upon cooling. It is the
most reactive nonmetallic element and extremely powerful oxidizing agent.
Because of its extreme reactivity, fluorine does not occur uncombined in nature.
Fluorine occurs widely combined in the mineral fluorspar( fluorite, the chief
commercial source), cryolite and apatite. The preparation of the free element is
carried out by the electrolysis of a molten mixture of hydrogen fluoride, HF,
and potassium fluoride, KF in the absence of water. Fluorine can be safely
stored under pressure in cylinders of stainless steel if the valves of the
cylinders are free from traces of organic matter. The outstanding oxidizing
properties of the elemental gas are used in some rocket fuels. The element may
be used for the fluorination of organic compounds with appropriate precautions.
The element is used for manufacturing various fluorides including chlorine
trifluoride ans cobalt(III) fluoride which are important fluorinating agents for
organic compounds, sulfur(VI) fluoride used as a gaseous electrical insulator.
Boron trifluoride and antimony trifluoride like hydrogen fluorides are important
catalysts for alkylation reactions used to prepare organic compounds. Sodium
fluoride (NaF) is used to treat dental caries and is often used for the
fluoridation of drinking water to reduce tooth decay (However, there are reports
of an accompanying risk of fluoride toxicity ). The element is also used for the
preparation of uranium(VI) fluoride, utilized in the gaseous diffusion process
of separating uranium-235 from uranium-238 (natural uranium) for reactor fuel.
The importance of fluorine lies largely in its extreme ability to attract
electrons and to the small size of its atoms, which can be attributed to form
many stable complexes with positive ions like hexafluorosilicate(IV) and
hexafluoroaluminate(III). Fluorine derivatives of hydrocarbons (compounds of
carbon and hydrogen) are useful extensively as aerosol-spray propellants,
refrigerants, solvents, cleansing agents for electrical and electronic
components, and foaming agents in shipping-plastics manufacturing. Useful
plastics with non-sticking qualities, such as polytetrafluoroethylene ( known by
the trade name Teflon), are readily made from unsaturated fluorocarbons. A
solution of hydrogen fluoride gas in water is called hydrofluoric acid, largely
consumed for cleaning metals and for polishing, frosting, and etching glass.
Hydrofluoric acid is also used as a catalyst for alkylation reactions. The
chemical reactions are similar to those in the sulfuric acid process, but it is
possible to avoid refrigeration. (In sulfuric acid alkylation, refrigeration is
necessary because of the heat generated by the reaction). Sodium Fluorosilicate
show similar application with sodium
fluoride in the field of laundry souring, manufacturing
enamels, manufacturing coated papers, wood
preservative , foam
production, opal glass, ore