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Einsteinium (Es): structure, properties, obtaining, uses

Actinoids are a series whose first member is actinium and are part of the so-called internal transition elements . Einsteinium is also the seventh transuranic element, as it is located seven places ahead of uranium in the periodic table of elements.

Symbol, atomic number and standard atomic mass of einsteinium. me / CC BY-SA (https://creativecommons.org/licenses/by-sa/2.5). Source: Wikimedia Commons.

It is a very radioactive solid and once formed it begins to disintegrate forming other elements, which has made it very difficult to study it. Although the number of possible isotopes of einsteinium is large, only less than 20% have been discovered.

Einsteinium has no commercial uses. It is produced in very small quantities in nuclear laboratories and is intended solely for scientific experiments. In addition, researchers in such trials use it in very few micrograms and with due precautions, since exposure to its radiation is lethal.

Nomenclature

  • Einsteinium, chemical symbol: Es
  • Einsteinium-253, Es-253 or 253 Es: isotope of einsteinium with an atomic mass of 253.

Discovery

Source

This element was first identified by Albert Ghiorso (a US nuclear scientist) and his collaborators in December 1952 in fragments dispersed by the thermonuclear explosion of the first hydrogen bomb test.

This H-bomb, called “Ivy Mike” and also “the sausage” because of its shape, was detonated in November of the same year on an island belonging to a Pacific coral atoll.

Ivy Mike hydrogen bomb explosion. US Department of Energy / Public domain. Source: Wikimedia Commons.

A uranium fission bomb had been used to detonate it. The latter’s atoms captured several neutrons during the explosion and underwent various steps of beta decay, each emitting an electron and a proton, leading to the formation of einsteinium-253, an isotope of Es.

An isotope is a variant of the same element that has a different number of neutrons in the nucleus of the atom, so it has the same atomic number (in this case 99) but different atomic mass. The isotope number indicates its atomic mass.

Publication of the finding

The work was initially kept secret, but after a year the authors decided to publish it for fear that other independent scientists might produce it in other laboratories, get credit for the discovery, and name the element.

So from November 1953 to March 1954 they reported four of its isotopes. Finally, in the summer of 1955, the discovery of the new element einsteinium with atomic number 99 was announced.

The nuclei of atoms have protons and neutrons. The isotopes of an element are atoms of the element that have different numbers of neutrons in their nucleus. Author: Gerd Altmann. Source: Pixabay.

It is important to note that the collection of the samples from the thermonuclear explosion claimed the life of First Lieutenant Jimmy Robinson, who was exposed to their radiation for a long time.

Name selection

The name “einsteinium” was chosen because Albert Einstein laid some of the foundations of quantum theory that would later explain how atoms interact with each other.

The most significant thing about the presence of his name is the application of his famous equation E = mc 2 , which explains the conversion of mass into energy in the most destructive weapons created by man.

Albert Einstein disagreed with the use of science to create destructive weapons. Author: Stux. Source: Pixabay.

The authors of the discovery suggested that the element had the symbol “E”, but in 1957 the International Union of Pure and Applied Chemistry , or IUPAC ( International Union of Pure and Applied Chemistry ), changed the symbol to “Es”.

Electronic structure

Its electronic configuration is:

2 ; 2 2 2 6 ; 3 2 3 6 3 10 ; 4 2 4 6 4 10 4 14 ; 5 2 5 6 5 10 ; 6 2 6 6 ; 5 11 7 2 ,

or in summary form:

[Rn] 5 11 7 2 ,

where [Rn] is the electronic structure of the noble gas radon (which is also radioactive).

Schematic of the orbitals and electrons of an einsteinium atom, according to an improved Bohr model. Ahazard.sciencewriter / CC BY-SA (https://creativecommons.org/licenses/by-sa/4.0). Source: Wikimedia Commons.

Einsteinium properties

Physical state

Metallic solid at room temperature.

Atomic mass

252,083

Melting point

860 ºC

Boiling point

996 ºC

Chemical properties

Studies with 253 Es show that its behavior is that which is typically observed in a trivalent actinide element, that is, the +3 valence predominates in its reactions.

Some of the compounds with oxidation state +3 have been characterized, such as chloride (EsCl 3 ), bromide (EsBr 3 ), iodide (EsI 3 ), oxychloride (EsOCl) and oxide (Es 2 O 3 ) .

Image of einsteinium iodide taken in the dark. Light is caused by the emission of radioactivity. Los Alamos National Lab. / Public domain. Source: Wikimedia Commons.

However, valences +2 and +4 have also been reported, although they have not been confirmed. In this case, it would be the first divalent metal in the actinide series.

X-ray crystallographic data for this element and its compounds are very difficult to obtain because their spontaneous decay produces gamma radiation and X-rays that overexpose the instrument’s detector and film.

Isotopes

So far, 19 isotopes of Es have been discovered with atomic masses between 241 and 257, and 3 isomers. Neither is stable. However, of all the possible isotopes of einsteinium, less than 20% have been produced and identified.

Its most stable isotope is einsteinium-252, which has a half-life of 471.7 days. It decays to berkelium-248 through the emission of an alpha particle (made up of 2 protons and 2 neutrons) or becomes californium-252 by capturing an electron.

Current obtaining

Today, einsteinium is produced by a long chain of nuclear reactions that involves bombarding each isotope in the chain with neutrons and ultimately the resulting isotope undergoes beta decay.

In beta decay or decay, the nucleus of the atom emits a beta particle, which can be an electron or a positron, to balance the neutron / proton ratio in the nucleus of the atom.

Process

In Oak Ridge laboratories in the United States, about 3 micrograms (μg) have been produced in the High Flux Isotope Reactor or HFIR ( High Flux Isotope Reactor ). A microgram is one millionth of a gram, that is, it is equivalent to 0.000001 gram.

The method has been the following:

  • Large amounts (kilograms) of 239 Pu (polonium-239) were irradiated over several years to produce 242 Pu.
  • The 242 Pu was converted to plutonium oxide and mixed with aluminum oxide Al 2 O 3 to form compressed spheres.
  • The spheres of the material were incorporated into special bars to be irradiated for a year at the Savannah River Plant in the United States.
  • The bars were then irradiated in the HFIR for a further 4 months.
  • Finally, the resulting material was subjected to chemical procedures to separate the einsteinium from the californium isotopes (children of Es).
Nucleus of an atom. Polonium nuclei are bombarded with neutrons as part of the procedure to obtain einsteinium. Author: Clker-Free-Vector-Images. Source: Pixabay.

In special HFIR operations, up to about 2 milligrams (mg) of einsteinium can be obtained.

Applications

This element has only been produced in very small quantities, it is also very radioactive, so it has no commercial use. It currently has application only in basic scientific research.

In obtaining mendelevium

In 1961 it was possible to produce a macroscopic quantity of 253 Es with a weight of 0.01 micrograms (μg) measured with a special magnetic type balance. This sample was then bombarded with neutrons to produce the element mendelevium (atomic number 101).

In studies on the effects of radiation

The intense self-emission of radiation from einsteinium can be used to study accelerated aging and radiation damage.

Radiation emitted by einsteinium-253. Photo taken in the dark. Haire, RG, US Department of Energy.Touched up by Materialscientist at en.wikipedia. / Public domain. Source: Wikimedia Commons.

For example, it has been used in studies of the chemical consequences of radioactive decay.

Due to the relatively short half-life of Es-253 (20.47 days), both the internal growth of its daughter isotope Bk-249, whose half-life is 330 days, and that of the grandson Cf-249 (life mean of 351 years).

Certain data suggest that divalent Es could decay to divalent berkelium and possibly divalent californium (as yet unknown).

In chemical and physicochemical studies

It is the heaviest element with which studies can be carried out that allow the development of fundamental investigations about the role played by 5 f electrons in the organization and classification of actinides.

The Es-252 is available only in minimal quantities. The isotopes Es-253 (half-life 20.47 days) and Es-254 (275.7 days) have a longer half-life and there is a greater availability of these, which is why they are used in physicochemical studies.

However, usually only a few micrograms (μg) are used in experiments to reduce worker exposure and minimize the effects of intense self-irradiation.

Einsteinium is very dangerous because it is a powerfully radioactive element. Author: Clker-Free-Vector-Images. Source: Pixabay.

Potential use in medicine

It is believed that it could be used for medical radiation treatments directed at certain organs.

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