Einsteinium elements

There are several spaces in the Periodic Table between plutonium (element 94) and einsteinium (element 99). But by 1952 these had already been filled by scientists at Berkeley, using the cyclotron to bombard heavy nuclei with particles that, when captured, increased the nuclear mass. In 1944 Glenn Seaborg, Albert Ghiorso, and Ralph James made elements 95 and 96 this way. Kept secret until after the war, they were respectively called americium and curium. 

This dial is registering disintegrations of single atoms of einsteinium, element 99, which was isolated in the October 1956 napkin-ring operation. 

The new element mendelevium was made by bombarding einsteinium, element 99, with helium nuclei. 

The use of larger particles in the cyclotron, for example carbon, nitrogen or oxygen ions, enabled elements of several units of atomic number beyond uranium to be synthesised. Einsteinium and fermium were obtained by this method and separated by ion-exchange. and indeed first identified by the appearance of their concentration peaks on the elution graph at the places expected for atomic numbers 99 and 100. The concentrations available when this was done were measured not in gcm but in atoms cm. The same elements became available in greater quantity when the first hydrogen bomb was exploded, when they were found in the fission products. Element 101, mendelevium, was made by a-particle bombardment of einsteinium, and nobelium (102) by fusion of curium and the carbon-13 isotope. 

Albert Einstein) Einsteinium, the seventh transuranic 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 20-day 253Es isotope was produced. 

In 1961, enough einsteinium was produced to separate a macroscopic amount of 253Es. This sample weighted about O.OlMg and was measured using a special magnetic-type balance. 253Es so produced was used to produce mendelevium (Element 101). 

Tracer studies using 253Es show that einsteinium has chemical properties typical of a heavy trivalent, actinide element. 

Each of the elements has a number of isotopes (2,4), all radioactive and some of which can be obtained in isotopicaHy pure form. More than 200 in number and mosdy synthetic in origin, they are produced by neutron or charged-particle induced transmutations (2,4). The known radioactive isotopes are distributed among the 15 elements approximately as follows actinium and thorium, 25 each protactinium, 20 uranium, neptunium, plutonium, americium, curium, californium, einsteinium, and fermium, 15 each herkelium, mendelevium, nobehum, and lawrencium, 10 each. There is frequently a need for values to be assigned for the atomic weights of the actinide elements. Any precise experimental work would require a value for the isotope or isotopic mixture being used, but where there is a purely formal demand for atomic weights, mass numbers that are chosen on the basis of half-life and availabiUty have customarily been used. A Hst of these is provided in Table 1. 

It is possible to prepare very heavy elements in thermonuclear explosions, owing to the very intense, although brief (order of a microsecond), neutron flux furnished by the explosion (3,13). Einsteinium and fermium were first produced in this way they were discovered in the fallout materials from the first thermonuclear explosion (the "Mike" shot) staged in the Pacific in November 1952. It is possible that elements having atomic numbers greater than 100 would have been found had the debris been examined very soon after the explosion. The preparative process involved is multiple neutron capture in the uranium in the device, which is followed by a sequence of beta decays. Eor example, the synthesis of EM in the Mike explosion was via the production of from followed by a long chain of short-Hved beta decays,... 

The effects of a rather distinct deformed shell at = 152 were clearly seen as early as 1954 in the alpha-decay energies of isotopes of californium, einsteinium, and fermium. In fact, a number of authors have suggested that the entire transuranium region is stabilized by shell effects with an influence that increases markedly with atomic number. Thus the effects of shell substmcture lead to an increase in spontaneous fission half-Hves of up to about 15 orders of magnitude for the heavy transuranium elements, the heaviest of which would otherwise have half-Hves of the order of those for a compound nucleus (lO " s or less) and not of milliseconds or longer, as found experimentally. This gives hope for the synthesis and identification of several elements beyond the present heaviest (element 109) and suggest that the peninsula of nuclei with measurable half-Hves may extend up to the island of stabiHty at Z = 114 andA = 184. 

Glenn Theodore Seaborg (1912-1999), Albert Ghiorso ( 1915), together with Bernard G. Harvey, Gregory Robert Choppin ( 1927), and Stanley Gerald Thompson (1912-1967). Bombardment of einsteinium-253 with alpha particles allowed the detection of 17 atoms of element... 

Like einsteinium, this unstable element was discovered in the fallout from the first hydrogen bomb. To date, only fragments in microgram amounts can be isolated. 258Fm ends the series of transuranium elements that can be produced in a reactor by neutron bombardment. The longest-lived isotope decays with a half-life of 100 days... 

Radioactive, short-lived element. The longest-lived isotope (256Md) has a half-life of 55 days. To date, only a few atoms have been prepared by a nuclear reaction between einsteinium and helium nuclei in a particle accelerator. 

Element 100 wurde auf die gleiche Weise wie Einsteinium von Ghiorso u. Mitarb. (93) in Staubproben aus der Mike -Testexplosion aufgefunden. Es konnte in Gestalt eines a-Strahlers, von 16 Std Halb-... 

These elements have all been named for famous scientists or for the places of their creation. For example, americium, berkelium, and californium were named after obvious geographical locations. Nobelium was named for the Nobel Institute, although later study proved it was not really created there. Curium was named for Marie Curie, the discoverer of radium. Einsteinium was named for the famous physicist, Albert Einstein. Fermium and lawrencium were named for Enrico Fermi and Ernest O. Lawrence, who made important discoveries in the field of radioactivity. Mendelevium was named for the discoverer of the periodic chart. 

Since plutonium is the actinide generating most concern at the moment this review will be concerned primarily with this element. However, in the event of the fast breeder reactors being introduced the behaviour of americium and curium will be emphasised. As neptunium is of no major concern in comparison to plutonium there has been little research conducted on its behaviour in the biosphere. This review will not discuss the behaviour of berkelium, californium, einsteinium, fermium, mendelevium, nobelium and lawrencium which are of no concern in the nuclear power programme although some of these actinides may be used in nuclear powered pacemakers. Occasionally other actinides, and some lanthanides, are referred to but merely to illustrate a particular fact of the actinides with greater clarity. 

Einsteinium - the atomic number is 99 and the chemical symbol is Es. The name derives from Albert Einstein , the German bom physicist who proposed the theory of relativity. A collaboration of American scientists from the Argonne National Laboratory near Chicago, Illinois, the Los Alamos Scientific Laboratory in Los Alamos, New Mexico and at the University of California lab in Berkeley, California first found Es in the debris of thermonuclear weapons in 1952. The longest half-life associated with this unstable element is 472 day Es. 

Einsteinium belongs to group 13 (IIIA) of the heavy transuranic subseries of elements found in the actinide series. It was discovered after World War II, sometime in 1952, as a trace 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 atoll was obliterated, literally wiped off the face of the Earth, several heavy elements, both known and unknown at that time, were detected in the aftermath of the explosion by a team of scientists led by Albert Ghiorso of the Berkeley laboratory. Einsteinium was one of these trace elements that was detected. Its existence, as well as several other discovered elements, was not announced until 1955, due to secrecy related to this new type of thermonuclear bomb. The melting and boiling points as well as the density of einsteinium are not known because of the extremely small amounts that have been produced. 

Einsteinium does not exist in nature and is not found in the Earth s crust. It is produced in small amounts by artificial nuclear transmutations of other radioactive elements rather than by additional explosions of thermonuclear weapons. The formation of einsteinium from decay processes of other radioactive elements starts with plutonium and proceeds in five steps as follows ... 

Einsteinium, as an actinide metal, has several compounds similar to other transuranic elements that are formed with some of the nonmetals, as follows einsteinium dioxide (EsO ), einsteinium trioxide (Es O ), einsteinium trichloride (EsCy, einsteinium dibromide (EsBr ), and einsteinium triiodide (EsI ). 

The radioisotopes of einsteinium are highly unstable and radioactive. The small amount of the 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 nuclear materials who must take precautions in handling exotic elements. 

Before their experiment that produced mendelevium, the team had speculated that this element number 101 must be somewhat similar to the element thulium ( Tm) located just above it in the lanthanide series. Because they did not have a name for this new element, they referred to it as eka-thuhum, with an atomic number of 101. It was formally named mendelevium in 1955 only after they were able to produce a few atoms of einsteinium by the nuclear process as follows gjEs-253 + —> Md-256 + n-1 (a neutron with a mass of... 

This article presents a general discussion of actinide metallurgy, including advanced methods such as levitation melting and chemical vapor-phase reactions. A section on purification of actinide metals by a variety of techniques is included. Finally, an element-by-element discussion is given of the most satisfactory metallurgical preparation for each individual element actinium (included for completeness even though not an actinide element), thorium, protactinium, uranium, neptunium, plutonium, americium, curium, berkelium, californium, and einsteinium. 

The vapor pressures at 1473 K of a few of the actinide elements and other materials of interest are given in Table III. All of the actinide (An) elements through einsteinium can be obtained by this process ... 

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