einsteinium Chemische Eigenschaften,Einsatz,Produktion Methoden
Physikalische Eigenschaften
Einsteinium belongs to group 13 (IIIA) of the heavy transuranic subseries of elementsfound in the actinide series. It was discovered after World War II, sometime in 1952, as atrace element in the residue from the massive explosion of the hydrogen bomb on Eniwetok Atoll in the Marshall Islands, located in the West Central Pacific Ocean. Although the atollwas obliterated, literally wiped off the face of the Earth, several heavy elements, both knownand unknown at that time, were detected in the aftermath of the explosion by a team of scientistsled by Albert Ghiorso of the Berkeley laboratory. Einsteinium was one of these traceelements that was detected. Its existence, as well as several other discovered elements, was notannounced until 1955, due to secrecy related to this new type of thermonuclear bomb. Themelting and boiling points as well as the density of einsteinium are not known because of theextremely small amounts that have been produced.
Isotopes
There are total of 20 isotopes of einsteinium. Einsteinium is not found innature. All the isotopes are radioactive and are produced artificially. Their half-lives rangefrom eight seconds to 472 days. None have exceptionally long half-lives.
Origin of Name
Named after and in honor of the famous physical scientist Albert Einstein.
Occurrence
Einsteinium does not exist in nature and is not found in the Earth’s crust. It is produced insmall amounts by artificial nuclear transmutations of other radioactive elements rather than byadditional explosions of thermonuclear weapons. The formation of einsteinium from decay processesof other radioactive elements starts with plutonium and proceeds in five steps as follows:
1.
239Pu →2 neutrons + gamma rays →
241Pu →
241Am + β-.
2.
241Am → 1 neutron + gamma →
242Am →
241Cm + β-.
3.
242Cm → 7 neutrons + gamma →
249Cm →
249Bk + β-.
4.
249Bk → 1 neutron + gamma →
250Bk →
250Cf + β-.
5.
250Cf → 3 neutrons + gamma →
253Cf →
253Es + β-.
Charakteristisch
Einsteinium’s most stable isotope, einsteinium-252, with a half-life of 472 days, decays intoberkelium-248 through alpha decay, and then into californium-252 through beta capture. Itcan also change into fermium-252 through beta decay.
Einsteinium has homologous chemical and physical properties of the rare-earth holmium(
67Ho), located just above it in the lanthanide series in the periodic table.
History
Einsteinium, the seventh transura-
The Elements 4-11
nic element of the actinide series to be discovered, was identified
by Ghiorso and co-workers at Berkeley in December 1952
in debris from the first large thermonuclear explosion, which
took place in the Pacific in November 1952. The isotope
produced was the 20-day
253Es isotope. In 1961, a sufficient
amount of einsteinium was produced to permit separation of
a macroscopic amount of
253Es. This sample weighed about
0.01 μg. A special magnetic-type balance was used in making
this determination.
253Es so produced was used to produce
mendelevium. About 3 μg 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. 254Es has the longest
half-life (276 days). Tracer studies using 253Es show that
einsteinium has chemical properties typical of a heavy trivalent,
actinide element. Einsteinium is extremely radioactive.
Great care must be taken when handling it.
Verwenden
Einsteinium does not really have any common uses except as related to research in nuclearand chemical laboratories.
Definition
einsteinium: Symbol Es. A radioactivemetallic transuranic elementbelonging to the actinoids; a.n. 99;mass number of the most stable isotope254 (half-life 270 days). Elevenisotopes are known. The element wasfirst identified by A. Ghiorso and associatesin debris from the first hydrogenbomb explosion in 1952.Microgram quantities of the element did not become available until 1961.It is named after Albert Einstein.
Hazard
The radioisotopes of einsteinium are highly unstable and radioactive. The small amount ofthe element and its compounds produced are not likely to be available in most laboratories.Thus, they do not pose any general hazard except in the case of scientists working with nuclearmaterials who must take precautions in handling exotic elements.
Industrielle Verwendung
Element 99, called einsteinium, was originallynamed ekaholmium because it appears tohave chemical properties similar to holmium. Itis produced by bombarding uranium-238 withstripped nitrogen atoms. It decays rapidly toform the lighter berkelium, or element 97. Neptunium(element 93), californium (element 98),and illinium (element 61), are also made atomically.The latter also has the names florentiumand promethium.
einsteinium Upstream-Materialien And Downstream Produkte
Upstream-Materialien
Downstream Produkte
