Mendelevium: divalency and other chemical properties

Area of Science:

• Radiochemistry
• Actinide Chemistry
• Solution Chemistry

Background:

• Mendelevium (Md), element 101, is a synthetic actinide.
• Understanding the oxidation states and solution chemistry of heavy elements is crucial for nuclear science and chemistry.

Purpose of the Study:

• To investigate the solution chemistry of mendelevium.
• To determine if mendelevium can form a stable divalent ion.
• To characterize the redox behavior of mendelevium.

Main Methods:

• Reduction of mendelevium from the 3+ oxidation state using various reducing agents (Zn dust, Zn-Hg amalgam, Cr(2+), Eu(2+), V(2+)).
• Equilibrium measurements with V(2+) to estimate the redox potential of the Md(2+)/Md(3+) couple.
• Comparison of Md(3+) chemical behavior with other trivalent actinides and lanthanides.

Main Results:

• Mendelevium was successfully reduced to a stable divalent ion (Md(2+)) in solution.
• The redox potential for the Md(2+)/Md(3+) couple was estimated to be approximately +0.2 V.
• The chemical behavior of Md(3+) was found to be similar to trivalent actinides and lanthanides.
• Oxidation of Md(3+) to higher oxidation states using sodium bismuthate was not observed.

Conclusions:

• Mendelevium is the first actinide element capable of forming a stable divalent ion in solution.
• The divalent state of mendelevium exhibits distinct redox properties compared to its trivalent state.
• The chemical similarity of Md(3+) to other trivalent f-elements is confirmed.