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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: Cooper on November 09, 2012, 02:29:03 PM

Title: Why are oxygen-oxygen bonds weak?
Post by: Cooper on November 09, 2012, 02:29:03 PM

Hello,

I've been reading about ozonolysis and radicals and my textbook keeps mentioning how weak oxygen-oxygen bonds are, like in ozanides. Why are these bonds so weak? I think it's from electron repulsion.  But then why aren't other bonds like Br-Br bonds weak (or are they?), they have more valence electrons.  ???

Thanks,
~Cooper

Title: Re: Why are oxygen-oxygen bonds weak?
Post by: orgopete on November 10, 2012, 09:46:56 AM

Why are O-O bonds so weak? Good question. I think this is part of what Pauling was attempting to explain when he created electronegativity theory. If you look as homolytic bond strength, I-I<Br-Br<Cl-Cl>F-F. Why are I-I bonds weak and why aren't F-F bonds stronger? From bond energy, more energy is released upon breakage of the bonds of the smaller atoms. If the bond is also weaker, fluorine is very reactive. I expect oxygen should be similar. At this point, I find it easier to simply remember this than to provide a universal principle that can explain it.