States vs Real Charges

The systems of valent states and oxidation states introduced by chemists are not merely electron accounting systems. They are the systems which allow us to understand and predict which ratios of elements will form compounds and also suggests what are the likely structures and properties for these compounds (3). In the case of highly covalent compounds, the actual occupancy of the parent orbitals may seem to be very different than that implied from oxidation states if ionicity were high. Nonetheless, even some physicists have recognized the fundamental validity and usefulness of the chemist s oxidation state approach where the orbitals may now be described as symmetry or Wannier orbitals (6). 

The oxidation state situation in the oxidized copper oxides is O 11 and mixed Cun-CuIH by definition. There is no implication in this designation that the charge on copper has greatly increased beyond that of a pure Cu11 oxide. The electron was not removed from copper, but rather an antibonding electron was removed from the Cu-O bond. 

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There continues to be great confusion about the meaning of formal oxidation states vs. real charges on ions. As expected this is more of a problem in the physics communityf but it is unfortunately also a problem in parts of the chemistry community. When one writes Ba2BiIIIBiv0 f there is no implication that the real charges on bismuth cations should resemble +3 and +5. 

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