The Oxidation State of Transition Metals

The Chemistry of Art > 4. The Transition Metals > The Oxidation State of Transition Metals >

Why transition metals may have more than one oxidation state

  • Transition metals have multiple oxidation states
    • Due to ability to lose electrons from both the 3d and 4s subshells
  • It doesn’t take large amounts of energy for oxidation to occur because the 4s and 3d subshells are of similar energy levels
    • Therefore they are easily reduced or oxidised
    • High oxidation state = Good oxidising agent (Likely to reduce)
  • Each oxidation state exhibits different colours

General tip:

  • Main group metals
    • Oxidation states equal periodic table group number
  • Transtion metals
    • Oxidation states often less than their group number
  • Manganese
    • 0 – Mn(s)
    • 2+ – Mn2+(aq)
    • 3+ – Mn(OH)3 (s)
    • 4+ – MnO2 (s)
    • 6+ – MnO4-2 (aq)
    • 7+ – MnO4 (aq)
  • The +2 oxidation state occurs in nearly all transtion metals
    • Due to loss of the two 4s electrons
  • States above +2 results from additional loss of 3d electrons
    • When simple charged ions are formed
    • When transtion metal is bonded to more electronegative elements
  • Maximum oxidation states equal the total number of 4s and 3d electrons
    • From scandium to manganese, the maximum oxidation state increases from +3 to +7
    • Beyond manganese, the maximum oxidation states decrease and +3 and +2 are most prominent