Redox trends of the first row transition metals

[orgohell]

Hey, I'm having trouble understanding the trends of the oxidation states for the first row of the transition metals

-my prof said that Cu is the only metal that forms a stable +1 oxidation state. But, I've done a question in hmwrk that had Cu+1 as unstable with respect to disproportionation how can it be both stable and unstable?

-The frost diagram for the transition metals has all (except Cu) with negative 2+/3+ oxidation states. Does this mean that the oxidation reaction M(metal)⇔M^z+ +ze^- is thermodynamically favoured as the reduction couple (slope of the line) is negative?

Thanks a lot!

 

[Borek]

my prof said that Cu is the only metal that forms a stable +1 oxidation state. But, I've done a question in hmwrk that had Cu+1 as unstable with respect to disproportionation how can it be both stable and unstable?

Stability is not a simple TRUE/FALSE concept. There are Cu(I) compounds that can be stored forever (think chalcocite) when isolated. But in water solutions, or in contact with air, they are not stable, and will either get oxidized or disproportionate.