American chemist · 1927–2015
Gregory R. Choppin
Gregory Choppin was a young postdoctoral researcher at Berkeley when he helped make and identify mendelevium in 1955.
How Mendelevium was found
Choppin worked on the ion-exchange chemistry used to separate the new element. The team used a technique Choppin helped refine, eluting with alpha-hydroxyisobutyrate, which separated neighbouring actinides cleanly and showed that the new atoms came out exactly where element 101 should.
Shared the credit
The discovery is credited jointly to these scientists.
Life and career
Born 1927 · Died 2015
Choppin was born in Eagle Lake, Texas, and earned his PhD at the University of Texas. He spent most of his career at Florida State University, where he became a world authority on the chemistry of the actinides and lanthanides and on radioactive waste.
Discovered in the same era
Other elements identified within ten years of 1955.