What is oxidation number stand for?

Answer 1

Oxidation number is usually taken to be the notional charge of an atom following a predetermined set of rules to assign electrons. As such it is an electron counting formalism.

Wikipedia has a confusing write up which has been ultimately caused by IUPAC who have contradictory definitions in their naming and gold book documentation. The rules in wikipedia are a commonly applied set- although some chemists adhere to different rules that assign electrons to the most electronegative atom- it depends where you were taught.

In coordination chemistry, the oxidation number of a central atom in a coordination compound is the charge that it would have if all the ligands were removed along with the electron pairs that were shared with the central atom.

The oxidation number (previously called the Stock number, is used in the nomenclature of inorganic compounds. It is represented by a Roman numeral. The oxidation number is placed either as a right superscript to the element symbol, for example FeIII, or in parentheses after the name of the element, iron(III): in the latter case, there is no space between the element name and the oxidation number.

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