Electron delocalization in Benzophenone

[GPhab]

Homework Statement

Are all the atoms except the hydrogens involved in electron delocalization in benzophenone?

Homework Equations

The Attempt at a Solution

Yes as the double bonds are in conjugation. But we were told that the answer is no. Can anybody explain why this so?

 

[GCT]

Distinguish between the pi and sigma electrons. I am not certain whether the pi bond on the carbonyl group participates with the benzenes , at the moment I am not able to envision it doing so.

 

[raglandrb]

i would think that because of the stability of the two benzene rings they are very well delocalized, however oxygen from the carbonyl would give a partial negative charge itself and the carbon a partial positive, leaving a dipole moment towards oxygen. All carbons in the benzene ring DO contribute to the delocalization in the conjugated pi bonds, but the oxygen does not because its tendency is to want to take the electrons from carbon. if that makes sense.