It eats through glass, sets water on fire, and makes metals burn. Fluorine is the most reactive element in the entire periodic table. No other atom craves electrons with such ferocity. Its electronegativity of 3.98 is the absolute record. Even the noble gases xenon and radon cannot resist its pull.
Yet this destructive force also works for us. Fluoride in toothpaste shields enamel from decay. The non-stick coating on your frying pan is a fluoropolymer. Your air conditioner runs on a fluorine-based refrigerant. Without fluorine, there would be no uranium enrichment and no dozens of modern medicines.
In its pure form, fluorine is a pale yellow gas with a sharp, suffocating smell. It is so aggressive that only containers made of nickel or Monel alloy can hold it. Ordinary glass, rubber, and most metals crumble on contact.
Fluorine is the only halogen with no positive oxidation states. Its compounds are everywhere: in toothpaste, non-stick coatings, refrigerants, and pharmaceuticals. The mineral fluorite (CaF₂) has been known since the 16th century, but pure fluorine eluded chemists for nearly 80 years.
Fluorine is one of the most dangerous elements. Gaseous F₂ causes severe chemical burns to skin, eyes, and lungs. A concentration of 25 ppm is hazardous, and 100 ppm can be lethal within minutes. Hydrofluoric acid (HF) is especially insidious: it penetrates the skin painlessly, destroying bones and tissues from within. Working with fluorine requires specialized nickel or Monel equipment and strict safety protocols.
Fluorine is so reactive that water, glass, and even brick ignite on contact with it. No other substance can do that.
Isolating pure fluorine took 74 years of failed attempts. Several chemists were poisoned or killed. Henri Moissan won the Nobel Prize for finally succeeding in 1906.
Teflon (PTFE) was discovered by accident in 1938. This fluoropolymer has one of the lowest friction coefficients known — almost nothing sticks to it.
About 20% of modern pharmaceutical drugs contain fluorine atoms. It boosts molecular stability and improves how the body absorbs the medication.
Fluorine-19 is the only stable isotope of fluorine. This makes it a monoisotopic element — a rarity in nature.
Fluorine's electronegativity is 3.98 on the Pauling scale — the highest of any element. It literally steals electrons from everything it touches.
| Isotope | Mass (u) | Abundance | Half-life | Decay |
|---|---|---|---|---|
19F | 18.998403 | 100.00% | stable | — |
Electrolysis of potassium bifluoride