Fluorine

Fluorine is the most reactive of all elements, a pale yellow gas that attacks almost anything it touches, even glass. It was so dangerous to isolate that several chemists were injured trying, until Henri Moissan succeeded in 1886. It is mined as the mineral fluorite, a form of calcium fluoride.

Once bonded, fluorine becomes remarkably stable. It is used in fluoride toothpaste, nonstick pan coatings, refrigerants and the processing of uranium for nuclear fuel. In the television, fluorine atoms on the liquid crystal molecules give them a strong electrical imbalance, so they turn sharply in an electric field while staying stable and pure for years.