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16 Cards in this Set

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Delocalized Electrons
electrons that are shared by more than 2 atoms (usually by a line of electrons) IN THE SAME PLANE
Kekule Structures
shows possible stagnit molecules
Actual Structures
shows the sharing of pie bonds within molecule (COMPRIMISE)
Benzene
a)planar
b)carbon atom (sp2)= 3 sigma bonds
c)3 sigma bonded to 2C and H atoms
d)Unhybridized p orbitals (parallel/sideways<DOUGHNUT> =pie bond)
e)Pie~above and below plane ring
f)PIE ELECTRONS= shared by all six carbons DELOCALIZED
Resonance
(aka= resonance structure or resonance contributor) compound with delocalized electrons; approximate structures using localized electrons
Resonance Hybrid
(aka= actual structure) average of all resonance structures
Drawing Resonance Contributors
a)only PIE or NONBONDED ELECTRONS move
b)total number of paired or unpaired electrons doesn't change
c)move electrons toward sp2 (pos charge, pie charge, or radical) or sp3 with nonbonded electrons
Predicted stabilities or resonance contributors
each rc may be more stable than the other= <the greater the predicted stability of the resonance contributor, the more it contributes to the resonance hybrid>
Factors that increase predicted stability of (CRS)
a) all atoms octet
b) neg charges on the most electronegative atom/ pos charges on the least electronegative atom
c)charge (and/or charge seperation) can be destabilized
Resonance Energy
Extra stability a compound gains having delocalized electrons
a)greater # of relatively stable RC, the greater RE
b)more nearly equivalent RC, greater RE
Delocalized electrons
are electrons that are shared by
more than 2 atoms
Benzene
a)planar.
b)each carbon atom is sp2 hybridized= 3 σ bonds with two other carbon atoms and
one hydrogen atom.
c)unhybridized p orbitals are
parallel and overlap sideways= doughnut
shaped π orbital (above and below the plane of the ring)
<The π electrons are therefore shared by all six carbon>
atoms
Electron delocalization
occurs only when all atoms sharing the delocalized electrons lie in the same plane, so their p orbitals can effectively overlap.
A compound with delocalized electrons
have each approximate structure using localized
electrons is called a resonance structure or resonance
contributor.
Resonance hybrid
The actual structure is called an average of all resonance structures
Allylic and benzylic cations
have delocalized electrons,
are more stable than similarly substituted
carbocations with localized electrons.