what element is f

The element with the symbol F is Fluorine. Fluorine is a highly reactive, pale yellow-green gas and is the lightest halogen. It is the most electronegative and oxidizing element, and reacts with all other elements except for the light inert gases. Fluorine is used in the nuclear power industry to separate uranium isotopes and to make sulfur hexafluoride, the insulating gas for high-power electricity transformers. It is also used in toothpaste and water fluoridation to prevent tooth decay.