consider any molecular shape and takes into account only the filling of the valence
shell (8 electrons model); (2) the valence electron pair repulsion (VSEPR) theory
which rationalizes the molecular shape in terms of the minimum pair repulsion,
keeping the couples of bound atoms each ones separated in their interaction (also
using hybrid orbitals).
The symmetry-adapted molecular orbitals takes as molecular orbitals those
which are base of the irreproducible representation in the symmetry group of the
molecule.
Step by step the model implementation goes from the only consideration of the
electron number, to the total consideration of electrons and orbitals of the molecules, assessing that the bond is in charge to all the atomic orbitals, not only to those
linking two atoms. By this way (see water molecule), both the shape and some
reactivity can be rationalized. The spectroscopic experimental data (XPS) are in
agreement with this symmetry approach.
It can be suggested that the symmetry constitutes a unifying approach to treat the
chemical bond, as well as the molecular symmetry has the function of including all
the constituents of the chemical bonds in the entire molecule. No energy is implied
in the symmetry operations, and thus, the symmetry is only a way to describe in an
easy way the electronic properties and to suggest that the symmetry is a condition to
whom the electrons must obey.
As for the unique value of the symmetry, it has been invoqued also in the music
composition; it was suggested that several composers, mainly Ludwing Van
Beethoven, assembled the musical text by using measures related by symmetry
operations. This guaranties the correlation among the various sections of the music
score and the unit of it.
2.5 Considerations About the Models of Chemical Bond in Use Before …
37
shell (8 electrons model); (2) the valence electron pair repulsion (VSEPR) theory
which rationalizes the molecular shape in terms of the minimum pair repulsion,
keeping the couples of bound atoms each ones separated in their interaction (also
using hybrid orbitals).
The symmetry-adapted molecular orbitals takes as molecular orbitals those
which are base of the irreproducible representation in the symmetry group of the
molecule.
Step by step the model implementation goes from the only consideration of the
electron number, to the total consideration of electrons and orbitals of the molecules, assessing that the bond is in charge to all the atomic orbitals, not only to those
linking two atoms. By this way (see water molecule), both the shape and some
reactivity can be rationalized. The spectroscopic experimental data (XPS) are in
agreement with this symmetry approach.
It can be suggested that the symmetry constitutes a unifying approach to treat the
chemical bond, as well as the molecular symmetry has the function of including all
the constituents of the chemical bonds in the entire molecule. No energy is implied
in the symmetry operations, and thus, the symmetry is only a way to describe in an
easy way the electronic properties and to suggest that the symmetry is a condition to
whom the electrons must obey.
As for the unique value of the symmetry, it has been invoqued also in the music
composition; it was suggested that several composers, mainly Ludwing Van
Beethoven, assembled the musical text by using measures related by symmetry
operations. This guaranties the correlation among the various sections of the music
score and the unit of it.
2.5 Considerations About the Models of Chemical Bond in Use Before …
37