|Boiling Point: unknown
Melting Point: 1133oK, 860oC, 1580oF
Electron Energy Level: 2, 8, 18, 32, 29, 8, 2
Isotopes: 19 + None Stable + 3 Meta States
Heat of Vaporization: unknown
Heat of Fusion: unknown
Specific Heat: unknown
Atomic Radius: ~860 pm
Ionic Radius: 0.925Å
Electronegativity: 1.3 (Pauling); 1.2 (Allrod Rochow)
1s2 2s2p6 3s2p6d10 4s2p6d10f14 5s2p6d10f11 6s2p6 7s2
Einsteinium, named for Albert Einstein, was the seventh transuranic element of the actinide series to be discovered. It was first identified in December 1952 by Albert Ghiorso at the University of California, Berkeley and another team headed by G.R. Choppin at Los Alamos National Laboratory. Both were examining debris from the first thermonucleaar explosion (hydrogen bomb test), which took place in the Pacific in November 1952 (Operation Ivy). They discovered the isotope 253Es (half-life 20.5 days) that was made by the nuclear fusion of 15 neutrons with 238U (which then went through seven beta decays). These findings were kept secret until 1955 due to the Cold War.
In 1961, a sufficient amount of einsteinium was synthesized to prepare a microscopic amount of 253Es. This sample weighed about 0.01 mg. A special magnetic-type balance was used in making this determination. 253Es so produced was used to produce mendelevium (Element 101). About 3 mg of einsteinium has been produced at Oak Ridge National Laboratories by irradiating for several years kilogram quantities of 239Pu in a reactor to produce 242Pu. This was then fabricated into pellets of plutonium oxide and aluminum powder, and loaded into target rods for an initial 1-year irradiation at the Savannah River Plant, followed by irradiation in a HFIR (High Flux Isotopic Reactor). After 4 months in the HFIR the targets were removed for chemical separation of the einsteinium from californium. Nineteen isotopes and isomers of einsteinium are now recognized. 252Es has the longest half-life (276 days). Tracer studies using 253Es show that einsteinium has chemical properties typical of a heavy trivalent, actinide element.
Today, einsteinium is produced though a lengthy chain of nuclear reactions that involves bombarding each isotope in the chain with neutrons and then allowing the resulting isotope to undergo beta decay. Since only small amounts of einsteinium have ever been produced, it currently has no uses outside of basic scientific research.
19 radioisotopes of einsteinium have been characterized, with the most stable being 252Es with a half-life of 471.7 days, 254Es with the longest half-life of 275.7 days, 255Es with a half-life of 39.8 days, and 253Es with a half-life of 20.47 days. All of the remaining radioactive isotopes have half-lifes that are less than 40 hours, and the majority of these have half lifes that are less than 30 minutes. This element also has 3 meta states, with the most stable being 254mEs (t½ 39.3 hours). The isotopes of einsteinium range in atomic massfrom 240.069 u (240Es) to 258.100 u (258Es).
252Es decays into berkelium-248 through alpha decay, into californium-252 through electron capture or into fermium-252 through beta decay.
There is currently no evidence of einsteinium evolved in any biological role. Due to its extreme rarity its only use is in scientific research.