The maximum oxidation state of reasonable stability in the transition metal of 3d series correspond to the sum of s and d-electrons upto Mn. However, after Mn there is an abrupt decrease in oxidation states. For details, consult Section. In the light of this, most stable oxidation states of the elements are :
`3d^(3):3d^(3)4s^(2)(+5),3d^(5):3d^(5)4s^(1)(+6)` and `3d^(5)4s^(2)(+7)`
`3d^(8):3d^(8)4s^(2)(+2),3d^(4):3d^(4)4s^(2)` or `3d^(5)4s^(1)(+6)`
