Fluorine Fluorine Fluorine is a chemical element with symbol F and atomic number 9. It is the lightest halogen and exists as a highly toxic pale yellow diatomic gas at standard conditions. As the most electronegative element, it is extremely reactive, as it reacts with almost all other elements, except for helium and neon. Among the elements, fluorine ranks 24th in universal abundance and 13th in terrestrial abundance. Fluorite, the primary mineral source of fluorine which gave the element its name, was first described in 1529; as it was added to metal ores to lower their melting points for smelting, the
Chemistry: A Volatile History all the elements in their order: Notice carbon and silicon are in Group IV and the volatile gases fluorine, chlorine and bromine are in Group VII. Mendeleev was sufficiently confident in the layout of his table that he was willing to leave gaps for unknown elements to make the pattern fit – believing other elements would later be discovered that filled the gaps. So, for Mendeleev to be vindicated, the gaps needed to be filled, and luckily, in 1859, new instrumentation had been developed for discovering elements. Robert Bunsen knew that when certain elements burned in the flames of his