Fluorine is a colorless gas in it's elemental state .
Of all the elements it is the most electronegative, the most reactive, the most nonmetallic, and the most potent oxidizing agent. Once reacted however, the substances it forms are some of the most stable and inert. Fluorine is rare in its elemental form since in tends to react with nearly anything. Fluorine can be extracted through the electrolysis of an anhydride such as potassium fluoride, but cannot be separated chemically because the fluorine reacts with any newly introduced agent. As a preventive measure against tooth decay some supplies of water in the United States are fluoridated at 1 ppm after it was observed that the residents of Deaf Smith County, TX, had better dental records attributed to the naturally fluoridated water.