CHEM 232 Exam 1 with 100% Correct
Answers
sigma bond - ANS-head on overlap
pi bond - ANS-side by side overlap (always formed with p orbitals)
bond order - ANS-reflects the strength of a bond
resonance - ANS-electron delocalization by shifting pi bonds and lone pairs
conjugation - ANS-electron delocalization by overlapping p orbitals
criteria for conjugated systems - ANS-composed of 3 or more p orbitals, p orbitals must
be on adjacent atoms, p orbitals must be aligned (parallel pi bond alignment)
enantiomerically pure - ANS-EE=1
racemate - ANS-E=0 (optically inactive)
nodes - ANS-where phase switches, more nodes = more energy
criteria for aromatic systems - ANS-requires a fully conjugated cyclic system and the
ring is flat
huckel's rule - ANS-aromatic systems contain 4n+2 pi electrons where n is any positive
integer
criteria for nonaromatic compounds - ANS-not cyclic, not fully conjugated, not flat or p
orbitals not aligned
empirical resonance energy - ANS-a value for the stabilization due to electron
delocalization
frost circles - ANS-draw circle, inscribe polygon with vertex pointing down, put mo at
each vertex, bisect circle (all MOs below are bonding, above are antibonding), fill
orbitals with pi electrons
antiaromatic criteria - ANS-cyclic conjugated system, flat ring, contains multiple of 4n pi
electrons
Answers
sigma bond - ANS-head on overlap
pi bond - ANS-side by side overlap (always formed with p orbitals)
bond order - ANS-reflects the strength of a bond
resonance - ANS-electron delocalization by shifting pi bonds and lone pairs
conjugation - ANS-electron delocalization by overlapping p orbitals
criteria for conjugated systems - ANS-composed of 3 or more p orbitals, p orbitals must
be on adjacent atoms, p orbitals must be aligned (parallel pi bond alignment)
enantiomerically pure - ANS-EE=1
racemate - ANS-E=0 (optically inactive)
nodes - ANS-where phase switches, more nodes = more energy
criteria for aromatic systems - ANS-requires a fully conjugated cyclic system and the
ring is flat
huckel's rule - ANS-aromatic systems contain 4n+2 pi electrons where n is any positive
integer
criteria for nonaromatic compounds - ANS-not cyclic, not fully conjugated, not flat or p
orbitals not aligned
empirical resonance energy - ANS-a value for the stabilization due to electron
delocalization
frost circles - ANS-draw circle, inscribe polygon with vertex pointing down, put mo at
each vertex, bisect circle (all MOs below are bonding, above are antibonding), fill
orbitals with pi electrons
antiaromatic criteria - ANS-cyclic conjugated system, flat ring, contains multiple of 4n pi
electrons
