Not occurring in nature, einsteinium (as the isotope einsteinium-253) was first produced by intense neutron irradiation of uranium-238 during the detonation of nuclear weapons.
All einsteinium isotopes are radioactive.
The other new elements discovered by Seaborg were americium (95), curium (96), berkelium (97), californium (98), einsteinium (99), fermium (100), mendelevium (101), nobelium (102), and seaborgium (106).
The material was first collected on filter paper by drone airplanes flying through the radioactive explosion clouds; later, einsteinium and element 100 (fermium) were positively identified in coral gathered from Enewetak Atoll.
He also was part of a team of researchers who discovered that two new elements (element 99, einsteinium, and element 100, fermium) had been created by the first hydrogen bomb when it was exploded over Enewetak atoll in the Marshall Islands in a 1952 test.
Despite the short half-lives and scarcity of einsteinium isotopes, einsteinium metal has been prepared in milligram (10−3 gram) amounts.
Great similarities in chemical behaviour are found in the actinoids of oxidation state +3 (actinium and uranium through einsteinium); furthermore, these ions are much like the lanthanoids of the same oxidation state.
In recent decades, new elements have generally been named for famous scientists, producing such monikers as nobelium and einsteinium, said Peter F. Rusch, a consultant in Mountain View, Calif., who leads the American Chemical Society committee on nomenclature, terminology and symbols.
Mixtures of the isotopes einsteinium-253 (20.5-day half-life), einsteinium-254 (276-day half-life), and einsteinium-255 (39.8-day half-life) can be produced by intensive slow-neutron irradiation of elements of lower atomic number, such as plutonium.
Einsteinium-255 and einsteinium-256 eject electrons to form isotopes of fermium (atomic number 100), and mendelevium (atomic number 101) isotopes have been produced by bombarding einsteinium-253 "targets" with alpha particles in cyclotrons or linear accelerators.
For example, spectroscopic evidence for einsteinium II) in the presence of the fluoride ion has been obtained.
