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Element · F

Fluorine

The most reactive element there is, and the reason non-stick pans are non-stick.

Fluorine is the most electronegative element and reacts with almost everything, including glass and water. Isolating it took chemists most of the nineteenth century, and several were seriously injured trying.

Paradoxically, the carbon-fluorine bond it forms is one of the strongest in organic chemistry, which is why fluoropolymers such as PTFE are chemically inert, heat-resistant and slippery. The same stability makes some fluorinated compounds extremely persistent in the environment — the property that makes them useful is the property that makes them difficult.

Uses

Fluorine's uses run through its compounds, since the element itself is too reactive to handle casually. Fluoropolymers — PTFE above all — give surfaces almost nothing sticks to and chemical resistance nothing else matches, which puts them in cookware, gaskets, and the lining of chemical plant.

Uranium enrichment depends on uranium hexafluoride, the only convenient gaseous uranium compound. Fluoride in water and toothpaste hardens tooth enamel, and a large share of modern pharmaceuticals contains at least one fluorine atom, which alters how the drug is metabolised.

Medium confidence Weak evidence

How we know: checked recently · only one source, so there is nothing to cross-check it against · stated directly by the source.

How this connects

Where a connection has been confirmed by an outside reference, that reference is named beside it.

is used as

  • Corrosion protection application · fluoropolymer linings resist chemicals that attack every metal

is extracted from

  • Fluorite mineral · the only significant source; hydrofluoric acid is made from it and everything fluorinated follows Wikidata

is found in

  • Polytetrafluoroethylene material · every available position on it, and the whole of the material's behaviour: the strongest bond in organic chemistry, packed tightly enough that nothing sticks and nothing attacks
  • Apatite mineral · substitutes within a solid solution — an individual specimen may hold little of it
  • Bastnäsite mineral
  • Fluorite mineral Wikidata
  • Lepidolite mineral · substitutes within a solid solution — an individual specimen may hold little of it
  • Topaz mineral · substitutes within a solid solution — an individual specimen may hold little of it Wikidata

is an input to

  • Polymerisation process · as tetrafluoroethylene, which is where a substantial share of industrial fluorine chemistry ends up

is produced by

  • Molten salt electrolysis process · electrolysis of potassium bifluoride, which is molten and conducts — there is no chemical oxidant strong enough to displace fluorine from a compound, so electricity is the only route and always has been

is associated with

  • The Montreal Protocol event · in the replacements as much as in the originals, which is why the argument moved from ozone to global warming potential rather than ending

Sources

  • Material World
    Our own writing
  • Wikimedia Foundation · Creative Commons CC0 1.0 Universal (public domain dedication)
  • US National Library of Medicine · Mixed — aggregated third-party content, rights retained by depositors
  • United States Department of Commerce · US Government work — public information, credit requested

Questions this page answers

Where it comes from, and what it becomes

Follow Fluorine back to what it starts as, and forward into what it becomes. Each step is a documented one — a real route material takes, not a chain of inference.

Upstream — what it comes from

  • Fluorine → is produced by (electrolysis of potassium bifluoride, which is molten and conducts — there is no chemical oxidant strong enough to displace fluorine from a compound, so electricity is the only route and always has been) → Molten salt electrolysis → takes as input (after concentration, as one of the two routes to lithium chloride) → Lepidolite
  • Fluorine → is extracted from (the only significant source; hydrofluoric acid is made from it and everything fluorinated follows) → Fluorite

Downstream — what it becomes

  • Fluorine → is an input to (as tetrafluoroethylene, which is where a substantial share of industrial fluorine chemistry ends up) → Polymerisation → produces (from ethylene; chain length and branching decide whether it is a milk bottle or a fibre) → Polyethylene → is associated with (its first significant use was radar cable insulation, and its existence was classified) → The wartime materials programmes complete chain
  • Fluorine → is associated with (in the replacements as much as in the originals, which is why the argument moved from ozone to global warming potential rather than ending) → The Montreal Protocol complete chain
  • Fluorine → is used as (fluoropolymer linings resist chemicals that attack every metal) → Corrosion protection
  • Fluorine → is an input to (as tetrafluoroethylene, which is where a substantial share of industrial fluorine chemistry ends up) → Polymerisation → produces (from ethylene; chain length and branching decide whether it is a milk bottle or a fibre) → Polyethylene → is used in (the cup, as cross-linked UHMWPE — the deliberately sacrificial surface, and the source of the debris that ends the device) → Joint replacement → is used in (around two million hip and knee replacements a year) → Medical devices
  • Fluorine → is an input to (as tetrafluoroethylene, which is where a substantial share of industrial fluorine chemistry ends up) → Polymerisation → produces (from ethylene; chain length and branching decide whether it is a milk bottle or a fibre) → Polyethylene → is used in (as the ethylene-vinyl-acetate encapsulant sealing the cells, which is also why a panel cannot be taken apart at end of life) → Solar panel → is used as (and the price fell roughly ninety-nine per cent in thirty years on thinner wafers, finer saws and rising cell efficiency) → Photovoltaics
  • Fluorine → is an input to (as tetrafluoroethylene, which is where a substantial share of industrial fluorine chemistry ends up) → Polymerisation → produces (from ethylene; chain length and branching decide whether it is a milk bottle or a fibre) → Polyethylene → is used as (as insulation around the conductor, not as the conductor) → Electrical conduction

These are the most distinct paths onward. Fluorine ends up in others besides.