Chemical Forums
Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: chunkmartinez on April 08, 2007, 11:25:12 PM
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I have a question thats driving me crazy! In the case of carbon monoxide, how can the oxygen Tripple bond with the carbon, if the oxygen only has 2 open bonds?
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Bonding actually is more complicated than simple lewis theory. There are a bunch of other molecules for which the simple lewis model doesn't work.
To get into the specifics requires either a lot of hand-waving, or some quantum mechanics.
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I think i know what you are saying. Are you refering to the atomic orbitals?(S,p,d), and how energy levels can combine and stuff?
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Yep. When looking at molecules like carbon monoxide, and even dioxygen, you need to look at how atomic orbitals combine to form molecular orbitals. Here's a brief intro to it:
(http://www.ch.ic.ac.uk/vchemlib/course/mo_theory/main.html)
Its also a good way to understand things like aromaticity, e.g. the bonding in benzene, and other anomalies of more traditional (lewis style) bonding theory. I suppose the take-home message is that one has to look at the electron distribution over the whole molecule, bonds are not necessarily all that localized.
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While bonding is clearly more complicated, the easy way to think about why CO has a triple bond is this: It's is far worse to have an atom without a full octet (as you would in CO with only a double bond) than it is to have a third bond from oxygen.