Oxidation Numbers (Oxidation States)
- An oxidation number (oxidation state) is the charge an atom would carry if the molecule or ion were completely ionic.
- For a neutral molecule or compound, the sum of the oxidation numbers (states) for each element in the molecule equals 0.
- For a charged molecule (ion), the sum of the oxidation numbers (states) for each element in the ion equals the charge on the ion.
Rules for Assigning Oxidation Numbers
- Fluorine is assigned an oxidation number of -1 in compounds
- Oxygen is assigned an oxidation number of -2 in compounds
- Oxygen fluorides
- Hydrogen is assigned an oxidation of +1 in compounds
- Group 1 elements (Alkali Metals) are assigned an oxidation number of +1 in compounds
- Group 2 elements (Alkaline-earth metals) are assigned an oxidation number of +2 in compounds
- An atom of any element in the free state has an oxidation number of 0
- Any monatomic ion has an oxidation number equal to its charge
- The sum of the oxidation numbers of all the atoms in formula equals the electrical charge shown with the formula
Examples: Calculating an Oxidation Number (oxidation state)
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