Chapter 14

Question 1

A nonaromatic compound such as an alkane, cycloalkane, alkene, or alkyne

Answer 1

Aliphatic compound

Question 2

A cyclic conjugated unsaturated molecule or ion that is stabilized by π electron delocalization; are characterized by having large resonance energies, by reacting by substitution rather than addition, and by deshielding of protons exterior to the ring in their 1H NMR spectra caused by the presence of an induced ring current

Answer 2

Aromatic compound

Question 3

A structure in which lines are used to represent bonds; the structure for benzene is a hexagon of carbon atoms with alternating single and double bonds around the ring, and with one hydrogen atom attached to each carbon

Answer 3

Kekulé structure

Question 4

A phenomenon resulting from existence of 4n+2 delocalized π-electrons (n = 0, 1, 2, …) in a planar, cyclic conjugated molecule that bestows upon it enhanced stability

Answer 4

Aromaticity

Question 5

An energy of stabilization that represents the difference in energy between the actual compound and that calculated for a single resonance structure; arises from delocalization of electrons in a conjugated system

Answer 5

Resonance energy

Question 6

A rule stating that planar monocyclic rings with (4n+2) delocalized π electrons (i.e., with 2, 6, 10, 14, …, delocalized π electrons) will be aromatic

Answer 6

Hückel’s rule

Question 7

Monocyclic hydrocarbon that can be represented by a structure having alternating single and double bonds. The ring size of an annulene is represented by a number in brackets, e.g., benzene is [6] annulene and cyclooctatetraene is [8] annulene

Answer 7

Annulene

Question 8

Cations and anions that fulfill the criteria for aromaticity (planarity, electron delocalization, and a Hückel number of π-electrons) and thus have additional (aromatic) stability

Answer 8

Aromatic ions

Question 9

An aromatic compound whose molecules have one or more benzene rings

Answer 9

Benzenoid aromatic compound

Question 10

An aromatic compound, such as azulene, that doesn’t contain benzene rings

Answer 10

Nonbenzenoid aromatic compound

Question 11

Cagelite aromatic molecules with the geometry of a truncated icosahedron (or geodesic dome). The structures are comprised of a network of pentagons and hexagons. Each carbon is sp2 hybridized; the remaining electron at each carbon is delocalized into a system of molecular orbitals that gives the whole molecule aromatic character

Answer 11

Fullerenes

Question 12

A compound whose molecules have a ring containing an element other than carbon

Answer 12

Heterocyclic compound