Fluorine
halogenProperties
| Property | Value |
|---|---|
| Atomic Mass | 18.998 amu |
| Category | halogen |
| Group | 17 |
| Period | 2 |
| Electron Configuration | 1s2 2s2 2p5 |
| Electronegativity | 3.98 (Pauling) |
| Oxidation States | -1 |
| Melting Point | 53.48 K (-219.7 °C) |
| Boiling Point | 85.03 K (-188.1 °C) |
| Density | 0.001696 g/cm³ |
| Discovered By | Henri Moissan (1886) |
About Fluorine
Fluorine sets the ceiling on the Pauling electronegativity scale at 3.98 — every other element is measured against it. That number is not just a curiosity: it explains why the C–F bond is the strongest single bond in organic chemistry (about 485 kJ/mol), why HF is a weak acid in water despite F being the smallest, most charge-dense halide, and why elemental F₂ will set fire to asbestos, glass wool, and even small samples of water. Isolating the gas is a chemistry-history horror story — Moissan finally pulled it off in 1886 by electrolyzing potassium bifluoride in liquid HF at –50 °C, using a platinum-iridium U-tube to keep the cell from being eaten alive. Once tamed in compounds, fluorine becomes one of the most useful elements in industry. Fluoride strengthens hydroxyapatite in tooth enamel by exchanging OH⁻ for F⁻ to form fluorapatite, which is harder and less acid-soluble. PTFE owes its inertness entirely to a sheath of C–F bonds wrapped around an all-carbon backbone. And about 30% of new pharmaceuticals carry at least one fluorine, usually for metabolic stability.
Fun Fact
Fluorine is so reactive that it cannot exist as a free element in nature — every atom of fluorine on Earth is locked in compounds. It took over 70 years of attempts by chemists before anyone managed to isolate it.
Common Uses
- Fluorapatite formation in tooth enamel via NaF and water-fluoridation programs
- PTFE polymer synthesis from tetrafluoroethylene for chemically inert coatings
- UF6 gaseous diffusion and centrifuge enrichment of fissile ²³⁵U
- HFC and HFO refrigerants (R-134a, R-1234yf) for air conditioning
- C–F bonds in 30% of new pharmaceuticals for metabolic-stability tuning