2. Fluorine is a nonmetallic chemical element with chemical symbol F and atomic number 9. Fluorine, one of halogen elements, belongs to group ⅶ A of the periodic table and is located in the second period of the periodic table. The elemental fluorine is F2, which is a pale yellow and highly toxic gas.
3. Fluorine gas is very corrosive and extremely active in chemistry. It is one of the most oxidizing substances and can even react with some inert gases under some conditions. Fluorine is a key element in special plastics, rubber and refrigerators (chlorofluorocarbons). Due to the special chemical properties of fluorine, fluorine chemistry plays an important role in the history of chemical development.