Fluorine is a chemical element with the symbol F and atomic number 9. It is a pale yellow-green gas at room temperature and is the most electronegative and reactive of all elements. Fluorine belongs to the halogen group in the periodic table and is commonly found in nature as part of various minerals and compounds, such as fluorite. Due to its high reactivity, fluorine is rarely found in its elemental form. It is used in various applications, including the production of fluorinated compounds for refrigerants, pharmaceuticals, and toothpaste. Fluorine plays a crucial role in enhancing the effectiveness of dental care by helping to prevent cavities.