Chemistry
Notes_______________________________________________________________________
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Resonance
Resonance is a way of describing delocalized electrons within certain molecules or
polyatomic ions where the bonding cannot be expressed by a single Lewis formula.A
molecule or ion with such delocalized electrons is represented by several resonance
structures. In other words, the possibility of different pairing schemes of valence
electrons of atom is called resonance and different structures thus arranged are called
resonance structures.(JD Roberts, JD Roberts, JD Roberts, JD Roberts… - 1959 -
authors.library.caltech.edu)
Requirements of Resonance:
1:The positions of nuclei must remain the same across all resonance structures;only the
electrons can move.
2:All resonance structures must have same total number of valence electrons and same
net charge.
3:The hybridization of atoms must stay the same in all resonance structures.
4:All structures should follow the octet rule as closely as possible.
5:Each resonance structures must have same number of lone pair.
(Streitwieser, CH Heathcock, EM Kosower… - 1992 - thetruthaboutstuff.com)
Effect of Resonance on Reactivity:
Resonance affect Reactivity by stabilizing a molecule through delocalizing electron
density , which generally leads to lower reactivity. However resonance also increase
reactivity by creating localized areas of high or low electron density that are particularly
susceptible to attack by electrophile or nucleophile respectively.The specific effect
depends on molecule and type of substituent present.(RW Taft Jr, IC Lewis -
Tetrahedron, 1959 - Elsevier)
Effect of Resonance on stability:
Molecules with resonance are more stable than those that cannot be represented by single
Lewis structure. This extra stability is called resonance energy. Resonance increase stability of
molecules by delocalizing electrons, spreading out electrons density and formal charge over
multiple atoms. This delocalization lowers the molecule’s overall energy, making it less reactive
and more stable than a molecule with localized electrons.A molecule that can be represented by
Notes_______________________________________________________________________
_____
Resonance
Resonance is a way of describing delocalized electrons within certain molecules or
polyatomic ions where the bonding cannot be expressed by a single Lewis formula.A
molecule or ion with such delocalized electrons is represented by several resonance
structures. In other words, the possibility of different pairing schemes of valence
electrons of atom is called resonance and different structures thus arranged are called
resonance structures.(JD Roberts, JD Roberts, JD Roberts, JD Roberts… - 1959 -
authors.library.caltech.edu)
Requirements of Resonance:
1:The positions of nuclei must remain the same across all resonance structures;only the
electrons can move.
2:All resonance structures must have same total number of valence electrons and same
net charge.
3:The hybridization of atoms must stay the same in all resonance structures.
4:All structures should follow the octet rule as closely as possible.
5:Each resonance structures must have same number of lone pair.
(Streitwieser, CH Heathcock, EM Kosower… - 1992 - thetruthaboutstuff.com)
Effect of Resonance on Reactivity:
Resonance affect Reactivity by stabilizing a molecule through delocalizing electron
density , which generally leads to lower reactivity. However resonance also increase
reactivity by creating localized areas of high or low electron density that are particularly
susceptible to attack by electrophile or nucleophile respectively.The specific effect
depends on molecule and type of substituent present.(RW Taft Jr, IC Lewis -
Tetrahedron, 1959 - Elsevier)
Effect of Resonance on stability:
Molecules with resonance are more stable than those that cannot be represented by single
Lewis structure. This extra stability is called resonance energy. Resonance increase stability of
molecules by delocalizing electrons, spreading out electrons density and formal charge over
multiple atoms. This delocalization lowers the molecule’s overall energy, making it less reactive
and more stable than a molecule with localized electrons.A molecule that can be represented by
