Page 188 - Academic Press Encyclopedia of Physical Science and Technology 3rd Organic Chemistry
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Encyclopedia of Physical Science and Technology EN011G-539 July 14, 2001 21:48
Organic Chemical Systems,
Theory
Josef Michl
University of Colorado
I. Classical Bonding Theory
II. Qualitative Molecular Orbital Model of Electronic
Structure
III. Quantitative Aspects of Molecular Structure
IV. Reaction Paths
GLOSSARY φ 1 and φ 2 is given by φ 1 Hφ 2 dτ, where integration
is over all space.
Electron affinity Energy released when an electron is Ionization potential Minimum energy that must be pro-
brought from infinity and added to a molecule (it may vided to a molecule in order to remove one of its elec-
be negative if energy actually has to be provided). trons to infinity.
Electronegativity Measure of the tendency of an atom or Ortho, meta, para Designation of relative positions of
an orbital to attract and accommodate electron density. two substituents on a benzene ring: located on adjacent
Gradient of a surface The gradient at a point is a vector ring carbons (ortho), on next-nearest-neighbor ring car-
directed up the steepest slope of the surface at that bons (meta), and on carbons across the ring from one
point; its length is a measure of the slope. another (para).
Improper rotational axis of symmetry (of order n) A Pauli principle A wave function describing the state of
molecule is said to possess such an axis located in a a system containing two or more electrons is antisym-
particular direction if rotation by an angle 2π/n about metric with respect to the exchange of all coordinates
that direction, followed by mirroring in a plane perpen- of any two electrons (i.e., is converted to minus itself
dicular to the direction, converts the molecule back to on such an exchange). One of the consequences is that
itself. two electrons of the same spin cannot reside in the same
Inner-shell electrons Electrons in orbitals of energy orbital.
lower than that of the valence shell (closer to the
nucleus).
Interaction matrix element The interaction matrix ele- THE THEORY of organic chemistry deals with the funda-
ment of the Hamiltonian H between wave functions mental concepts that underlie and unify the experimental
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