Oxidation Number Rules

  1. The sum of all the Oxidation Number, ON, over all the atoms in a chemical species is equal to the charge on the chemical species
  2. In their compounds, the alkali metals and the alkaline earths have ON of +1 and +2 respectively.
  3. In compounds the ON of fluorine is almost always –1
  4. In compounds, the ON of hydrogen is usually +1
  5. In compounds, the ON of oxygen is usually –2.
  6. In binary (two-element) compounds with metals:
    Group 7A have ON of –1,
    Group 6A have ON of –2 and
    Group 5A have ON of –3.

Whenever two rules appear to contradict one another follow the rule that appears higher on the list.


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