Mendelevium

Mendelevium was first made in 1955 at Berkeley by Albert Ghiorso, Glenn Seaborg and colleagues, in a remarkable experiment that identified the new element from just seventeen atoms produced one at a time by bombarding einsteinium with alpha particles. It was named after Dmitri Mendeleev, the Russian chemist who created the periodic table. Mendelevium is an intensely radioactive synthetic metal, studied only atom by atom. Its most stable isotope lasts up to about two months and it is made only a few atoms at a time, yet enough has been studied to show that, unusually, it favours a more stable low oxidation state than its neighbours, a small chemical surprise wrung from single atoms.

The target for that landmark 1955 experiment was a barely visible speck of einsteinium, itself newly available only because of the Ivy Mike fallout analysis, electroplated onto a thin gold foil and bombarded for hours; the seventeen resulting mendelevium atoms were identified individually as they decayed, a technique so sensitive it could register a single new atom of matter, a milestone that validated the entire chain of heavy-element production techniques Berkeley had built up over the preceding decade. That same recoil-and-detect method, refined further, became the standard approach used to identify every heavier element discovered since.

Mendelevium's name honours Dmitri Mendeleev, whose periodic system, and whose confident predictions of undiscovered elements, had made the very map on which these new synthetic elements were being placed. Naming element 101 after him was a fitting tribute, but it was also, in the tense atmosphere of the Cold War, a pointed gesture, an American team choosing to honour a Russian scientist at a time of deep hostility between their nations. The experiment that found it was itself a landmark, demonstrating that chemistry could be done on single atoms, detected one by one as they decayed. Mendelevium has no ancient or esoteric tradition, being a synthetic element of 1955; its distinction is to carry the name of the man whose great chart it, and every other element, now occupies.

The gesture was reportedly well received in the Soviet Union, where Mendeleev remained a revered national scientific figure, and it stands as one of the few moments of quiet scientific goodwill exchanged between the two Cold War rivals even as they separately raced, sometimes bitterly, to claim credit for the elements that followed. Berkeley and Dubna would nonetheless spend much of the following two decades locked in exactly the priority disputes that this earlier gesture might have seemed to promise against.