Oxidation Numbers/States

• oxidation state - a number assigned to an atom that shows the charge that an atom has when electron pairs in covalent bonds belong entirely to the more electronegative atom
• oxidation states are used to kkeep track of electron transfer but does NOT represent an actual charge on an atom
• Atom/Ion: Oxidation #:

  all elements - 0

  simple ions - charge on the ion

  O2 - -2 (-1 in peroxides)

  H2 - +1 (-1 in hydrides
• • in all compounds the oxidation #'s must add up to the charge on the compound (0)
  • in all polyatomic ions the oxidation #'s must add up to the charge on the ion
  • may be useful to split up ionic compounds to "calculate" ox. #'s