| MadSci Network: Chemistry |
Almost all types of match use phosphorus. There are two allotropes of phosphorus. (An allotrope is a certain crystaline arrangement of atoms in an element. Most elements can have several possible crystaline arrangements of their atoms.) One allotrope of phosphorus is white, the other is red. White phosphorus is highly reactive and will ignite, given oxygen, with extremely little friction. It is therefore stored and cut under water. Red phosphorus,the other allotrope, is also quite reactive, but nowhere near as reactive as white phosphorus. Strike anywhere matches contain a white phosphorus tip. Just behind that tip is a mixture of oxidizers and reducers. (Just a bunch of chemicals put there to react and release a lot of heat.) This ignites the wood part of the match.
Safety matches are somewhat different. The match head contains oxidizers, reducers, and very fine particles designed to create friction. The striking surface is the key. It contains red phosphorus. The firction of a match head scraping against it causes a small amount of it to ignite. The heat from this is not enough to ignite the whole striking surface, because red phosphorus is not as reactive as white. It does, however, start the reaction between the oxidizers and reducers in the match head, which, again, light the wooden or cardboard part of the match.
If you tried to strike a safety match somewhere other than on the striker, it wouldn't create enough heat to start the reaction between the oxidizers and the reducers. But notice that if you give them heat, by putting a match head in a flame or against a hot burner on your stove, it will ignite.
P.S. One interesting note - cardboard matches are treated with a fire-retardant chemical. If they weren't, the match would burn up too fast.
a url containing a little on the history of matches: http://enterprise.shv.hb.se/~match/history.htm
Matthew Barchok, Mad Scientist
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