Oxidation Numbers

Gion Calzaferri
Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3000 Bern 9, Switzerland


The generally accepted rules for assigning oxidation numbers lead to the result that the oxidation number of the carbon atoms of a saturated pure hydrocarbon molecule can vary by four units, from -3 to zero, as e.g. in CH3CH2CH(CH3)C(CH3)3. This violates Jørgensens Axiom 2 which states: If there is no serious reason to do otherwise, identical oxidation numbers are ascribed to atoms of the same element in a given compound. I propose to change this uncomfortable situation without losing the very useful features of oxidation numbers and without making the rules complicated. The carbon group is so important that its non metals should be treated separately. This can be expressed as follows: The oxidation number for hydrogen is 0 in combination with C, Si, Ge, and also B, it is +1 in combination with non metals and -1 in combination with metals.

published in: J. Chem. Education 1999, 76, 362.

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