we review some of the crucial concepts. The
treatment is mainly qualitative, and for greater detail and
more rigorous derivations of mathematical relationships,
the references at the end of Chapter 1 should be consulted.
The development of quantum theory took place in two
stages. In the older theories (1900–1925), the electron was
treated as a particle, and the achievements of greatest significance
to inorganic chemistry were the interpretation of
atomic spectra and assignment of electronic configurations.
In more recent models, the electron is treated as a wave
(hence the name wave mechanics) and the main successes in
chemistry are the elucidation of the basis of stereochemistry
and methods for calculating the properties of molecules
(exact only for species involving light atoms).