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Elemental (pure) fluorine is the, or close to the, most reactive substance known to man. Almost anything placed in the path of a stream of fluorine gas will spontaneously burst into flame. This includes things like, oh, say glass, steel, and other things not normally thought of as flammable. It is, therefore, fairly difficult to have a sample of it in an element collection: There is no transparent container that will hold it. It can be stored in nickel cylinders, but then you can't see it, and you really wouldn't want one of those cylinders around.
The video for the first sample below is one made in the lab of Tryggvi Emilsson at the University of Illinois in the 1980s. Many other segments showing fluorine reacting with other substances were made, but appear to have been lost. (If you know of a copy of these videos please let me know!)
It might seem paradoxical that many compounds containing fluorine are extremely non-reactive, but actually this is two sides of the same coin. Fluorine is very reactive because it likes to bond very strongly with other atoms: Once that violent reaction has taken place, the fluorine is not about to let go again.
The best known non-reactive fluorine compound is teflon, discovered by accident and now used everywhere for its slipperiness and inertness, and which I use as my first fluorine sample.
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 Teflon thread seal tape.
When you screw together cast iron water or gas line pipe, you have to put thread seal compound or tape on the threads first, or else it will leak. The most popular choice is PTFE (polytetrafluoroethylene, otherwise known as teflon) tape, which is a soft, stretchable material that is very slippery and very resistant to chemical attack. This particular roll is pink, which is not characteristic of teflon, it's a dye added to indicate that this is thicker-than-usual tape.
Amazingly, on a weight-for-weight basis this tape is over 75% fluorine (the other 25% is carbon). Since pure fluorine is violently, explosively dangerous, having a 75% pure sample in a form you can hold isn't so bad.
PTFE tape is also a curious demonstration of the power of convention. It always comes on a particular kind of plastic spool, with a particular kind of snap-on cover to keep it clean. Every brand, every manufacturer, every store you look in, it's always exactly the same type of container. It would be fascinating to know the story of how this came about, but at this point the convention is so strong that if any manufacturer tried to sell teflon tape in a different package, they probably wouldn't sell more than a roll or two. Those would be returned as purchasing errors, because anyone who is looking for teflon tape will be looking for a particular shape of package, and won't even see any that's the wrong shape.
Source: Hardware Store
Contributor: Theodore Gray
Acquired: 15 April, 2002
Price: $2
Size: 2"
Purity: 75%
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Freon-22.
Freon-22 is Chlorodifluoromethane, or CHClF2. Not quite as much fluorine as teflon, but still quite a bit of it. This sample isn't exactly in the table, but it's over the table, in the air-conditioning system on the roof of our building.
Source: Ed Pegg Jr
Contributor: Ed Pegg Jr
Acquired: 11 September, 2002
Price: $0
Size: 18"
Purity: 44%
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Sample from the Red Green and Blue Company Element Set.
The Red Green and Blue company in England sells a very nice element collection in several versions. Max Whitby, the director of the company, very kindly donated a complete set to the periodic table table.
Almost all the samples in the set are very, very nice, but this one I have to tease a little bit. No doubt the glass ampule did at one time contain elemental fluorine: You can tell because it ate the glass on its way out. Glass will actually burn in a stream of pure fluorine (video coming soon). So there may be some silicon fluoride lining the inside of the glass, but there is virtually no chance that there is any element fluorine still inside.
To learn more about the set you can visit my page about element collecting for a general description or the company's website which includes many photographs and pricing details. I have two photographs of each sample from the set: One taken by me and one from the company. You can see photographs of all the samples displayed in a periodic table format: my pictures or their pictures. Or you can see both side-by-side with bigger pictures in numerical order.
For most sample from this set I have my own picture on the left and the one from the company here, but I haven't taken a picture of this sample yet so there's only one picture.
Source: Max Whitby of The Red Green & Blue Company
Contributor: Max Whitby of The Red Green & Blue Company
Acquired: 25 January, 2003
Price: Donated
Size: 0.2"
Purity: <5%
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Sample from the Everest Element Set.
Up until the early 1990's a company in Russia sold a periodic table collection with element samples. At some point their American distributor sold off the remaining stock to a man who is now selling them on eBay. The samples (excepted gasses) weight about 0.25 grams each, and the whole set comes in a very nice wooden box with a printed periodic table in the lid.
This sample is not marked as being a dummy (as the radioactive ones in the set are), but it obviously is. Elemental fluorine cannot be contained in glass: It eats the glass. There is, in fact, no known transparent substance able to contain it, so you simply can't have a sample of it that you can actually see.
To learn more about the set you can visit my page about element collecting for a general description and information about how to buy one, or you can see photographs of all the samples from the set displayed on my website in a periodic table layout or with bigger pictures in numerical order.
Source: Rob Accurso
Contributor: Rob Accurso
Acquired: 7 February, 2003
Price: Donated
Size: 0.2"
Purity: 0%
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