I have heard of liquid breathing, where an organism, usually a person, would be breathing in perfluorocarbon. Now I looked up perfluorocarbon on Wikipedia and I noticed, no oxygen at all, but fluorine that would rather bind to the molecules inside you and kill you. I mean, fluorine is electronegative enough to oxidize oxygen. So why doesn't perfluorocarbon fluoridate every oxygen molecule in your body preventing your cells from working and form calcium fluoride in your bones?
How would a person not be killed by breathing perfluorocarbon? Is oxygen more soluble in perfluorocarbon? Does perfluorocarbon not even get into the blood and instead stay in the lungs? And even then, why wouldn't the oxygen coming in be turned into oxygen fluoride? Is it simply because oxygen fluoride has such a short half-life, especially at body temperature that it never forms in significant enough amounts? But even then you would still be breathing out fluorine gas of which some will come back in the next breath. Fluorine gas is toxic because it is such a powerful oxidizer that it will oxidize anything.