Fluorine
Definition and meaning of Fluorine in chemistry.
![Fluorine element card: symbol F, atomic number 9, atomic mass 18.998, electron configuration [He] 2s² 2p⁵, oxidation states -1, Halogen, group 17, period 2, gas at room temperature.](/assets/images/terms/fluorine-chemical-element.webp)
Fluorine is a chemical element with the symbol F and atomic number 9. It belongs to the halogen group and exists as a highly toxic, pale yellow gas. As the most reactive element, it aggressively interacts with almost all other chemical elements.
In more detail
Fluorine sits at the very top of group 17 on the periodic table. Chemists characterize this element by its extreme reactivity and strong oxidizing capabilities. Fluorine possesses the highest electronegativity of all known chemical elements.
Electronegativity measures how strongly an atom attracts shared electrons in a bond. This strong attraction allows fluorine to form incredibly tough chemical bonds. It bonds particularly well with carbon atoms to create exceptionally stable fluorocarbon compounds.
In nature, you will almost never find fluorine as a free gas. Instead, it primarily exists trapped within mineral deposits like fluorite, cryolite, and fluorapatite. Pure fluorine gas is so reactive that it requires special handling.
It will spontaneously ignite when it comes into contact with many organic materials. The gas also rapidly corrodes nearly all common metals upon contact. Its unique chemical behavior allows it to stabilize other elements in their highest oxidation states.
An oxidation state shows the total number of electrons an atom has gained or lost. This stabilizing effect produces new chemical compounds with very unusual physical properties. Industrially, scientists isolate pure fluorine through a process called electrolysis. They run a strong electric current through a molten mixture of potassium fluoride and hydrogen fluoride.
Key facts
| Field | General Chemistry |
|---|---|
| Symbol | F |
| Atomic number | 9 |
| Atomic mass | 18.998 u |
| Category | Halogen |
| State at room temperature | Gas |
| Discovery year | 1886 |
Fluorine is absolutely indispensable in the chemical synthesis of polytetrafluoroethylene (PTFE). Most people know this popular synthetic polymer by its commercial brand name, Teflon. This material provides a famous non-stick and chemically inert surface for everyday cookware. Engineers also use it extensively to build advanced aerospace components and durable industrial tubing.
Frequently asked questions
Why is fluoride added to drinking water?
Cities add the fluoride ion to public water supplies to help prevent tooth decay. This helpful ion often comes from a liquid compound called fluorosilicic acid. It works by promoting the remineralization of dental enamel with strong, protective fluorapatite.
Can fluorine react with noble gases?
Yes, highly reactive fluorine can actually bond directly with some of the noble gases. Noble gases are generally famous for being completely unreactive under almost all normal conditions. However, fluorine is powerful enough to form stable chemical compounds with heavier noble gases like xenon.
Related terms
Sources & references
See our sources and editorial standards.