If all electrons shared in chemical bonds go to the more-electronegative atom, each atom has resultant charge {oxidation number}|. Oxidation number is number of electrons added to, or subtracted from, outer shell to make full shell. In molecules, atoms with higher electronegativity tend to gain electrons from atoms with lower electronegativity.
metals
Metals have positive oxidation numbers, because they lose electrons and empty outer shell. Metals are reducers, because they themselves oxidize.
non-metals
Oxygen and fluorine have negative oxidation numbers, because they gain electrons to fill outer shell. Oxygen and fluorine are oxidizers, because they themselves reduce.
hydrogen
Hydrogen can gain or lose one electron, making oxidation number +1 or -1.
others
Atoms can have several oxidation numbers, because they can fill or empty outer shell in different ways, through orbital hybridization.
functional group
Functional-group oxidation number is atom oxidation-number sum.
Physical Sciences>Chemistry>Inorganic>Oxidation-Reduction
5-Chemistry-Inorganic-Oxidation-Reduction
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Date Modified: 2022.0224