Einsteinium is a synthetic element with the symbol Es and atomic number 99 in the periodic table. It is the seventh transuranic element, and an actinide. It was discovered as a component of the debris of the first hydrogen bomb explosion in 1952, and named after Albert Einstein. Its most common isotope einsteinium-253 (half life 20.47 days) is produced artificially from decay of californium-253 in a few dedicated high-power nuclear reactors with a total yield on the order of one milligram per year. There are currently almost no practical applications for it outside of basic scientific research. In particular, einsteinium was used to synthesize, for the first time, 17 atoms of the new element mendelevium in 1955.
Einsteinium is a soft, silvery, paramagnetic metal. Its chemistry is typical of the late actinides, with a preponderance of the +3 oxidation state; the +2 oxidation state is also accessible, especially in solids. The high radioactivity of einsteinium-253 produces a visible glow and rapidly damages its crystalline metal lattice, with released heat of about 1000 watts per gram. Difficulty in studying its properties is due to einsteinium-253’s conversion to berkelium and then californium at a rate of about 3% per day. Einsteinium is the element with the highest atomic number which has been observed in macroscopic quantities in its pure form, and this was the common short-lived isotope einsteinium-253.
Because of the short half-life of all isotopes of einsteinium, all primordial einsteinium, that is einsteinium that could possibly be present on the Earth during its formation, has decayed by now. Synthesis of einsteinium from naturally occurring actinides uranium and thorium in the Earth crust requires multiple neutron capture, which is an extremely unlikely event. Therefore, most einsteinium is produced on Earth in scientific laboratories, high-power nuclear reactors, or in nuclear weapons tests, and is present only within a few years from the time of the synthesis. Einsteinium and fermium did occur naturally in the natural nuclear fission reactor at Oklo, but no longer do so. Einsteinium was observed in a very specular Przybylski’s Star 2008.
Like all synthetic transuranic elements, isotopes of einsteinium are extremely radioactive and are considered highly dangerous to health on ingestion. Edited from Einsteinium.
Thanks to Steve Barker for suggesting this post.