Aromaticity

Question 1

aromatic compounds

Answer 1

don’t undergo an addition reaction

Question 2

to be aromatic you must follow these rules

Answer 2

• have an uniterrupted cyclic cloud of pi electrons that are planar for overlapping (all must be sp2)
• pi cloud must have an odd # of electron pairs
• Huckel’s rule of 4n+2=# of pi electrons where n is a whole #

Question 3

Valence Bond theory

Answer 3

A covalent bond is formed by the overlap of 2 atomic orbitals and the electron pair in the resulting bond is shared by both atoms
- second row has hybrid orbitals to form sigma bonds (sp, sp2, sp3) and p orbitals for pi bonds

Question 4

Molecular Orbital Theory (MO)

Answer 4

Bonds are a combination of atomic orbitals that form a new set of orbitals
- 2 p orbs of similar phase overlap side by side and form a pi bonding MO
- 2 p orbs of opposite phase overlap and form a pi antibonding MO
- all bonding MOS are filled in aromatics

Question 5

3 classifications for a ring

Answer 5

• 1) aromatic (1+2)
• 2) antiromatic (1)
• 3) neither (none)

Question 6

Antibonding MO

Answer 6

Every atom is in opposite phases

Question 7

non bonding MO

Answer 7

nodes in the way to prevent bonding

Question 8

bonding MO

Answer 8

each atom is in the same phase

Question 9

how to determine the classification of heteroatoms

Answer 9

determine if they’re in sp2 (hybrid) or p (atomic)
- sp2 = DONT count for aromatic electrons
- p = DOES count for aromatic electrons
- no pi bonds= hybrid orbital (sp, sp2,sp3)