Fluorine Element Properties
Complete reference for Fluorine (F, element 9): atomic data, electron configuration, isotopes, physical constants, and chemical behavior.
Fluorine
Halogen — Period 2, Group 17
Atomic Identity
Electron Configuration
One unpaired electron in 2p — weakly attracted to magnetic fields
Isotopes of Fluorine
| Isotope | Symbol | Protons | Neutrons | Mass (u) | Natural Abundance | Stability |
|---|---|---|---|---|---|---|
| Fluorine-17 | ¹⁷F | 9 | 8 | 17.00209524 | Radioactive |
Unstable
β⁺ decay, t½ = 64.49 s |
| Fluorine-18 | ¹⁸F | 9 | 9 | 18.00093733 | Radioactive |
Unstable
β⁺/EC decay, t½ = 109.77 min |
| Fluorine-19 | ¹⁹F | 9 | 10 | 18.99840316 | 100% | Stable |
| Fluorine-20 | ²⁰F | 9 | 11 | 19.99998132 | Radioactive |
Unstable
β⁻ decay, t½ = 11.163 s |
Fluorine-19 is the only stable and naturally occurring isotope, making fluorine a monoisotopic element. Fluorine-18 is widely used as a radiotracer in positron emission tomography (PET) imaging due to its convenient half-life.
Physical Properties
Chemical Properties
Ground State Quantum Numbers
Notable Emission Lines
Fluorine produces a pale yellow flame in a flame test. Its strongest visible emission lines lie in the red-infrared region. The spectrum is best observed with a spectroscope due to fluorine's pale natural color.
Key Facts About Fluorine
Most Electronegative Element
Fluorine holds the highest Pauling electronegativity value of any element at 3.98. This extreme value results from its small atomic size, high effective nuclear charge, and seven valence electrons needing just one more to complete the octet. All C-F bonds and H-F bonds are strongly polarized toward fluorine.
Strongest Oxidizing Agent
Fluorine has the highest standard reduction potential (+2.866 V for F₂/F⁻), making it the strongest elemental oxidizing agent. It can oxidize noble gases like xenon and krypton and even reacts with glass (SiO₂) and many "inert" materials. It is one of the few elements that reacts directly with noble gases.
Monoisotopic Element
Fluorine-19 is the only stable isotope of fluorine with 100% natural abundance. This monoisotopic property makes fluorine extremely valuable in ¹⁹F NMR spectroscopy — it has spin-1/2, high sensitivity, and a wide chemical shift range, making it a useful probe in drug discovery and materials science.
Fluorine-18 in PET Imaging
Fluorine-18, with a half-life of about 110 minutes, is the most widely used radionuclide in positron emission tomography (PET). ¹⁸F-fluorodeoxyglucose (FDG) is the standard radiotracer for detecting cancer, measuring brain metabolism, and evaluating cardiac function. The convenient half-life allows synthesis and clinical use on the same day.
PTFE and Fluoropolymers
Polytetrafluoroethylene (PTFE, sold as Teflon) is made entirely of C-F bonds — the strongest single bonds in organic chemistry (bond energy ~485 kJ/mol). The C-F bond's strength and low polarizability give PTFE its extreme chemical inertness, non-stick properties, and thermal stability up to 260 °C. Fluoropolymers are used in cookware, electrical insulation, seals, and medical devices.
Industrial Hazard
Fluorine gas (F₂) and hydrofluoric acid (HF) are among the most dangerous industrial chemicals. HF penetrates tissue silently — causing systemic fluoride poisoning that interferes with calcium and magnesium metabolism. Even dilute HF on a small skin area can cause fatal cardiac arrhythmia. Emergency treatment uses calcium gluconate gel to neutralize fluoride ions.
Summary
Complete reference for Fluorine (F, element 9): atomic data, electron configuration, isotopes, physical constants, and chemical behavior.
How it works
- Browse the atomic identity section for symbol, atomic number, and standard atomic weight.
- Check the electron configuration panel for orbital notation and quantum numbers.
- Review the isotopes table for fluorine-19 abundance and radioactive isotope data.
- Consult the physical properties panel for melting point, density, and state at STP.
- Use the chemical properties section to understand halogen reactivity and ionization energies.
- Explore the key facts panel to learn about fluorine industrial uses and safety considerations.
Use cases
- Look up fluorine constants for chemistry homework or exams.
- Verify atomic data when writing lab reports or research papers.
- Reference electronegativity and bond polarity values for molecular chemistry.
- Check thermodynamic constants for materials science or engineering calculations.
- Teach or learn halogen group properties starting with the most reactive element.
- Confirm electron configuration before writing Lewis structures or molecular orbitals.
- Understand fluorine industrial applications in pharmaceuticals and polymers.
- Quick-reference ionization energy for electrochemistry or spectroscopy work.