What is 19f?

19F is the chemical symbol and atomic number for the element fluorine. It is the 13th most abundant element in the Earth's crust and is commonly used in toothpaste, refrigerants, and industrial chemicals. Fluorine is a highly reactive nonmetal and is the lightest member of the halogen group, which also includes chlorine, bromine, iodine, and astatine. It has a pale yellow color and is toxic and corrosive in its pure form. Fluorine is also used in the nuclear energy industry and is a key component for the synthesis of many pharmaceuticals.