I refer to a previous post by Ron on hyper conjugation in acetic acid(Link:https://chemistry stack exchange.com/.../hyper conjugation in-in-acetic-acid)wherein it is stated that "In acetic acid there is a partial positive charge on carbonyl oxygen". This is confusing me .How can oxygen carry a partial positive charge oxygen being highly electronegative?
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1$\begingroup$ In what post? Link? And what's your question really? Edit it! $\endgroup$– MithoronCommented Jul 21, 2017 at 14:39
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$\begingroup$ Partial positive charge of oxygen of carbonyl group in acetic acid . $\endgroup$– Hariharan VCommented Jul 28, 2017 at 4:26
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$\begingroup$ In a previous post by Mr. Ron "hyper conjugation of acetic acid ?" (Link- chemistry stack exchange.com/.../hyper conjugation-in-acetic acid")it s stated that "there is a partial positive charge on carbonyl oxygen ".How can oxygen hold a positive charge being electronegative? $\endgroup$– Hariharan VCommented Jul 28, 2017 at 5:09
1 Answer
The carbon atom does not have a full positive charge like a carbocation. What happens when a carbon atom is bound to a more electronegative element such as oxygen, is that the electron density from the bond is higher towards oxygen then carbon, therefore leaving the carbon atom with a partial positive charge. When drawing the chemical structure of a carbonyl compound, you can indicate that the carbon atom has a partial positive charge and the oxygen has partial negative charge by using the greek letter sigma as in the picture:
You can also see this through resonance structures for a carbonyl compound
The real molecule (the hybrid) is something between those two first structures in the left (they are called resonance structures and differ only by the electronic configuration around the atoms).