Mendelevium

In 1955 the Berkeley team bombarded about a billion einsteinium atoms with alpha particles and collected seventeen atoms of element 101 across several experiments — the birth of single-atom chemistry, in which an element is identified by the decay signature of individual nuclei rather than by any bulk property. The technique they used, recoil catching on a gold foil followed by ion-exchange elution, remains the template for every superheavy experiment since. Naming it for Dmitri Mendeleev at the height of the Cold War was a deliberate gesture by an American laboratory toward a Russian scientist, and it needed State Department clearance. Mendelevium is also notable for a genuinely unusual +2 oxidation state in solution.