benzene structures Flashcards
What is the structure of benzene?
Benzene has six carbon atoms joined in a ring with alternating single and double carbon bonds.
What is the formula of benzene?
Benzene has the formula C6H6.
What model was originally used to represent benzene?
Benzene was originally represented using the Kekule model.
How does the Kekule model depict benzene?
The Kekule model shows benzene as a ring of alternating single and double bonds with pi electrons localized between certain carbon atoms.
What model has replaced the Kekule model?
The delocalised model has replaced the Kekule model.
What evidence suggests the Kekule model is incorrect?
Three pieces of evidence suggest that the Kekule model wasn’t right.
What is the first piece of evidence against the Kekule model?
All carbon-carbon bonds in benzene are the same length, in-between that of a single and a double bond.
What is the second piece of evidence against the Kekule model?
Benzene is less reactive than alkenes.
What is the third piece of evidence against the Kekule model?
The enthalpy change of hydrogenation is lower than expected.
What is the significance of the p-orbitals in benzene?
In benzene, the p-orbitals of the carbon atoms overlap to form a pi-system.
How do the p electrons in benzene behave?
The sideways overlap of p electrons forms two regions of electron density above and below the plane of the carbon atoms, with the electrons delocalised over the whole ring.
How is the delocalised system of benzene represented?
The delocalised system is represented as a circle inside the hexagonal ring.
