Is the carbon in a carbonyl functional group electropositive? I had a professor tell me so, but I immediately refuted him, because he defined electronegativity earlier as the ability to stabilize negative charge ... and taking electronegativity to be a converse property, the strong partial positive character on the carbon probably isn't able to stabilize any further positive charge.
Similarly, I know that lone pairs are defined as having an electronegativity of 0 because electrons cannot stabilize other electrons.
The guy agreed with me. So, to confirm, am I correct, and, as an extension, can we describe the electron deficient carbon as electronegative instead? I could very well see a electron-deficient carbon stabilizing negative charge.
However, if we stick with the IUPAC definition of electronegativity - which is the ability to attract electrons, the carbonyl carbon still seems to lose to oxygen. A charge-separated resonance structure can be drawn for any carbonyl group with a + on carbon and a - on oxygen.
So that leads me to another question - is electronegativity the ability to stabilize negative charge or the ability to attract electrons within a covalent framework? I guess the two go hand in hand - i.e. you wouldn't attract electrons if you weren't able to stabilize them ...
As a side question: can we calculate EN for ions?