How do I go about calculating the oxidation number of sulphur in the thiosulphate ion, S2O32- ?
Igloo says Before calculating oxidation numbers of the elements in molecules and ions it is helpful to consider three rules: [1] The oxidation number of an element is 0 [2] The oxidation number of hydrogen is usually +1, except in hydrogen itself, H2, where it is of course 0, and in metal hydrides, e.g. NaH, in which it is -1. [3] The oxidation number of oxygen is usually -2, except in the element itself, O2, where the value is of course 0, in peroxides, e.g. H2O2, in which it is -1, and in the special case of oxygen difluoride, OF2, where it is +2. For molecules, the total oxidation numbers of all the atoms present must equal zero. For example in NO2 (nitrogen dioxide) since the oxidation number of oxygen is -2 (see rule 3 above), the value for nitrogen must be +4 (because +4 + 2x(-2) = 0). For ions, the total oxidation numbers of all the atoms present must equal the charge on the ion. For example, with the ammonium ion, NH4+, since hydrogen has an oxidation number of +1 (see rule 2 a
