2,4-Cyclopentadienone is unstable and cannot be isolated, whereas 2,4,6- cycloheptatrien...

2,4-Cyclopentadienone is unstable and cannot be isolated, whereas 2,4,6- cycloheptatrienone is quite stable and is readily isolated. Use arguments based on resonance and aromaticity to explain these experimental observations.

(Hint: Recall a resonance structure that is commonly written for the carbonyl group.)