Elemental Fluorine

Fluorine, the most electronegative element, is extremely chemically reactive. Fluorine chemically combines with every other element in the Periodic Table, except helium and neon, to form fluorides, and these reactions are often sudden or explosive. For this reason, Chemists didn't believe that it could be found in nature in its elemental form, they thought it would only ever be found in nature in ionic compounds such as in the mineral fluorite or fluorspar (CaF₂).
Chemists have now used ¹⁹F NMR spectroscopy to identify the presence of elemental fluorine in "stinking fluorspar" (antozonite, stinkspat, stinkfluss, stinkstein, fetid fluorite). As the name suggests, stinking fluorspar has an unpleasant, pungent odour when crushed.

For 200 years, scientists have tried to establish the cause of this unpleasant odour. Suggestions have included iodine and ozone, even sulfur, but Chemists doubted that elemental fluorine could be the cause of the odour. The elemental fluorine in stinking fluorspar is produced when the tiny amounts of uranium existing in the mineral emit ionizing radiation which splits the fluorite into calcium and element fluorine.

Reference
1.Jörn Schmedt auf der Günne, Martin Mangstl, Florian Kraus. Occurrence of Difluorine F2 in Nature-In Situ Proof and Quantification by NMR Spectroscopy. Angewandte Chemie International Edition, 2012; DOI: 10.1002/anie.201203515


Further Reading
Interactive Periodic Table
Trends in Group 17 (Halogens)
Electronegativity
Electron Configuration
Writing Ionic Formula
Name and Formula of Covalent Compounds
Balancing Chemical Equations

Suggested Study Questions

1. Give the symbol for each of the following elements:
   • fluorine
   • helium
   • neon
   • calcium
   • iodine
   • oxygen
   • sulfur
   • uranium
2. Explain what is meant by the term electronegative.
3. Give the electron configuration for fluorine in
• simple (shell) notation
• sub-shell notation
4. Give the chemical formula for elemental fluorine.
5. Explain why elemental fluorine is expected to exist as a covalently bonded molecule.
6. Give the formula for each of the following fluorides:
• calcium fluoride
• sodium fluoride
• lithium fluoride
• magnesium fluoride
• silver fluoride
• iron(II) fluoride
• tin(IV) fluoride
• gold(III) fluoride
• xenon difluoride
7. Write a balanced chemical equation to describe the reaction in which calcium fluoride in stinking fluorspar is split into elemental calcium and elemental fluorine.
8. Write balanced chemical equations for the production of the fluoride in each of the following reactions
• sodium metal and fluorine
• calcium metal and fluorine
• silver metal and fluorine
• iron metal and fluorine
• xeonon gas and fluorine
• hydrogen gas and fluorine