Mendelevium: divalency and other chemical properties.

Mendelevium (element 101) is the first actinide element found to give a divalent ion stable in solution. Reduction from the 3+ oxidation state was accomplished with Zn dust, Zn-Hg amalgam, Cr(2+), Eu(2+), and V(2+); additionally, measurements of the equilibrium with V(2+) provided an estimate of +0.2 volt for the couple, Md(2+) = Md(3+) + e(-). The chemical behavior of Md(3+) is similar to that of the other trivalent actinides and lanthanides. Oxidation from the trivalent to higher valence states with sodium bismuthate was not detected.