Why need oxygen for fire instead of another element?

Out of all the elements, what’s so special about oxygen that it is so intimately tied to fire?

Oh, fluorine would work just fine. Fortunately, it’s rare!
There are other “oxydizing” elements. Oxygen just happens to be common.


I think it’s pretty much just because it’s prevalent in the atmosphere, and it’s combustable.

Does that mean that in theory any “oxydizing” element (is that the same as “electronegative”?) would do the trick? Or is there something about, the energy given off by combustion has to be a net payoff, for the same reason that fusion in stars stops at Iron ?

Well, you do need a net energy payoff, and there are some substances which will “burn” in one element, but not another. Water, for instance, will burn in a fluorine atmosphere, but not in an oxygen atmosphere. I imagine, though, that carbon, say, or hydrogen, would burn in the presence of pretty much any electronegative element.

Yeah, any oxidizing element will do, if it’s in its free state. Therein lies the rub. Oxygen, I think, is the only oxidizer that is so stable at ambient temperatures that it can exist in its free state, yet has a low enough activation energy that it will support combustion in a self-sustaining manner. Certainly it’s the only common one in the atmosphere.

OK - now I can’t be the only one that’s dying to see what water looks like burning in fluorine??

I understand that a laboratory demonstration (that apparently used to be more cmmon) was to burn a candle in a chlorine atmosphere. That’s one reason there were so many science fiction stories about liens in chlorine atmospheres.

SF writer Hal Clement (Harry Clement Subbs) gave a lecture on the chemistry of such world a few years ago at the Arisia convention. He called it “Beachworld”. I get the mpression it was background for a story he never wrote.

No, it’s not necessarily so. There are classic laboratory demonstrations of fire not involving oxygen: for instance, magnesium burning in nitrogen producing magnesium nitride). “Fire” is merely an exothermic reaction involving a gas-phase interaction. Oxygen-related fires are just the most common.