Oxidation States

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Oxidation States
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• Oxidation State the apparent charge that an atom
  would have if electron pairs in covalent bonds
  belonged entirely to the more electronegative
  atom
• Oxidation Number positive or negative number
  assigned to an atom based on its oxidation state
• Electron bookeeping

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Common Oxidation Numbers(p. 658)
Atom or Ion Oxidation Examples
atoms in elements 0 Fe, C, O2, F2
hydrogen 1 HCl, NH3
hydrogen with metals -1 NaH, CuH2
oxygen -2 H2O, FeO, NO3-
oxygen in peroxides -1 H2O2
monoatomic ions ion charge Mg2, Na, S2-
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Determining Oxidation Numbers

• Assign common oxidation numbers
• The sum of oxidation numbers for a compound is 0
• The sum of oxidation numbers for a polyatomic ion
  is its charge
• Use algebra to determine any unknown oxidation
  numbers
• Examples
• K2SO4 K2Cr2O7 MnO4-

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Redox Reactions

• Oxidation numbers change in a redox reaction
• Oxidation is an increase in oxidation number
• Reduction is a decrease in oxidation number
• Ca(s) Cl2(g) ? CaCl2(s)
• CH4(g) 2O2(g) ? CO2(g) 2H2O(l)

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Practice

• Oxidation States of Vanadium Activity
• p. 659 12-14, 15a, 16, 17
• p. 662 18-20
• p. 663 1, 2, 5-8, 10