The element fluorine has 9 protons and 9 electrons. It is element number 9 on the periodic table and has a molar mass of 18.9 grams/moles.
Fluorine is the most reactive and lightest halogen on the periodic table and is found in group 17. It is also the most electronegative element, and can form compounds with almost every other element. In nature, fluorine exists as a yellow gas. Fluorine has many uses, and is commonly used in dental and pharmaceutical materials. The fluoride ion prevents dental caries from forming, and has been added to toothpastes and mouthwashes. It can also be found in tap water in many cities in the United States.