2.2F: Benzene and Resonance

why the hell is the chem quiz and hl essay Wednesday?

What are Orbitals?

regions where there is a high probability that electrons can be found

Tell me about benzene

• C6H6

• One of these structures is benzene, which contains a six-sided carbon ring with 120° bond angles

Tell me about the structure of benzene

• explanation for true structure of benzene is resonance

• Electrons in the double bonds of benzene are delocalized and can spread equally throughout the entire ring

• This results in carbon-carbon bonds that are equal in length and strength

What are the properties of Benzene?

• resonance makes benzene very stable

• Usually, substances with such a high carbon to hydrogen ratio are more reactive.

Tell me about Molecular Orbitals in regards to sigma bonds.

when two orbitals overlap head-on, a (sigma) σ-bond is formed. Each orbital donates one electron to the sigma bond. The two orbitals forming the σ-bond fuse into a molecular orbital. Both electrons would go into the molecular orbital

What bonds do σ-bonds form from? (# bond)

single

σ-bonds can form between which shapes?

between any shape of orbital

Tell me about (pi) π-bonds

• formed when two p-orbitals overlap side-to-side

• Each orbital donates an electron to the bond

• form double and triple bonds

• There are many π-bonds in benzene

  • The six electrons in those π-bonds are distributed into 3 molecular orbitals with two electrons in each orbital

What is the definition of Resonance?

when more than one Lewis structure can be drawn for a molecule

Tell me about Resonance Hybrids

• best descriptions of actual compound

• show delocalized electrons