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848 Chapter 28
Copyright © 2017 Pearson Education, Inc.
ground state
a description of which orbitals the electrons of an atom or a molecule occupy when
they are all in their lowest-energy orbitals.
highest occupied
the molecular orbital of highest energy that contains an electron.
molecular orbital (HOMO)
linear combination of
the combination of atomic orbitals to produce a molecular orbital.
atomic orbitals (LCAO)
lowest unoccupied
the molecular orbital of lowest energy that does not contain an electron.
molecular orbital (LUMO)
molecular orbital (MO)
a theory that describes a model in which the electrons occupy orbitals as they do
theory
in atoms but with the orbitals extending over the entire molecule.
pericyclic reaction
a concerted reaction that occurs as a result of a cyclic reorganization of electrons.
photochemical reaction
a reaction that takes place when a reactant absorbs light.
polar reaction
the reaction between a nucleophile and an electrophile.
radical reaction
a reaction in which a new bond is formed using one electron from one reactant and
one electron from another reactant.
selection rules
the rules that determine the outcome of a pericyclic reaction.
sigmatropic
a reaction in which a
s
bond is broken in the reactant, a new
s
bond is formed in
rearrangement
the product, and the
p
bonds rearrange.
suprafacial bond
formation and/or cleavage of two
s
bonds that occur on the same side of the
p
formation
system of the reactant.
suprafacial
a rearrangement where the migrating group remains on the same face of the
p
rearrangement
system.
symmetric molecular
a molecular orbital in which the left half is a mirror image of the right half.
orbital
symmetry-allowed
a pathway that leads to overlap of in-phase orbitals.
pathway
symmetry-forbidden
a pathway that leads to overlap of out-of-phase orbitals.
pathway
thermal reaction
a reaction that takes place without the reactant having to absorb light.
Woodward–Hoffmann
a series of selection rules for pericyclic reactions.
rules