An Overview about the Chemical Element Einsteinium

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Symbol: Es

Atomic Number: 99

Atomic Mass: 252.0 amu (atomic mass units)

Melting Point: 860C (1133 K or 1580F) 860C

Boiling Point: Unknown

Number of Protons: 99

Number of Electrons: 99

Number of Neutrons: 153

Classification: Rare Earth Metal

Group Name: Actinide or Actinoid

Crystal Structure: Unknown

Density @ 293 K: Unknown

Color: Unknown

The element einsteinium, named after the famous scientist Albert Einstein, was discovered in 1952. It had been formed by the detonation of the first hydrogen bomb in November 1952. A team of scientists under the leadership of Albert Ghiorso examined the debris left by the bomb at three laboratories: the Argonne National Laboratory, the Los Alamos National Laboratory and the University of California at Berkeley. In December they identified two new elements: einsteinium and fermium (element 100). These elements were originally kept secret owing to national security surrounding America's work on the hydrogen bomb.

The first isotope discovered was einsteinium-253, which has a half-life of 20.47 days and decays by either spontaneous fission or alpha decay. Einsteinium-253 was produced when atoms of uranium-238 were combined with 15 neutrons then went through 7 beta decays before the einsteinium atoms were formed.

The first measurable quantity of the element was formed in 1961 when 0.01 milligrams of einsteinium-253 was produced. This was subsequently used in the discovery of mendelevium (element 101).

Oak Ridge National Laboratories have been able to produce a larger quantity of einsteinium in a very lengthy process. They irradiated kilograms of plutonium-239 for several years in a reactor. This process produced plutonium-242, which was formed into pellets of plutonium oxide and aluminum oxide. The pelleted plutonium was place in rods for irradiation at the Savannah River nuclear plant for one year. Subsequently the rods were irradiated in a High Flux isotopic reactor for several months. The pellets were then processed chemically to separate the californium and einsteinium that had been produced. After all this the total amount of einsteinium produced was three milligrams.

With such a small amount of the element being produced it is no surprise that very little is known about einsteinium. Its ionization energy is 6.42 eV and its oxidation state is +3. A few einsteinium compounds have been made; other than dieinsteinium oxide (Es2O3) all of the compounds have been made with halogens. Einsteinium has formed: a trifluoride (EsF3), a dichloride (EsCl2), a trichloride (EsCl3), a tribromide (EsBr3), triiodide (EsI3) and a diiodide (EsI2). From its position in the periodic table einsteinium should be metallic and probably gray or white in color.

A number of different isotopes of einsteinium have been made. The mass numbers of the isotope formed to date range from 241 to 257. Einsteinium-252 has the longest half-life at 471.7 days. This isotope will decay by beta decay to form fermium-252, by alpha decay to form berkelinium-248 or by electron capture to form californium-252. The isotope with the shortest half-life at 8 seconds is einsteinium-241 which decays by alpha decay.

No industrial applications are currently known for einsteinium. As only a very small amount of the element has ever been formed and the process is so time consuming it is unlikely that it will ever be of use outside of scientific research.

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