Transuranium element

Last updated February 10, 2023

The transuranium elements (also known as transuranic elements) are the chemical elements with atomic numbers greater than 92, which is the atomic number of uranium. All of these elements are unstable and decay radioactively into other elements. With the exception of neptunium and plutonium (which have been found in trace amounts in nature), all do not occur naturally on Earth and are synthetic.

Overview

Of the elements with atomic numbers 1 to 92, most can be found in nature, having stable isotopes (such as hydrogen) or very long-lived radioisotopes (such as uranium), or existing as common decay products of the decay of uranium and thorium (such as radon). The exceptions are elements 43, 61, 85, and 87; all four occur in nature, but only in very minor branches of the uranium and thorium decay chains, and thus all save element 87 were first discovered by synthesis in the laboratory rather than in nature (and even element 87 was discovered from purified samples of its parent, not directly from nature).

All the elements with higher atomic numbers have been first discovered in the laboratory, with neptunium and plutonium later also discovered in nature. They are all radioactive, with a half-life much shorter than the age of the Earth, so any primordial atoms of these elements, if they ever were present at the Earth's formation, have long since decayed. Trace amounts of neptunium and plutonium form in some uranium-rich rock, and small amounts are produced during atmospheric tests of nuclear weapons. These two elements are generated from neutron capture in uranium ore with subsequent beta decays (e.g. ²³⁸U + n → ²³⁹U → ²³⁹Np → ²³⁹Pu).

All elements heavier than plutonium are entirely synthetic; they are created in nuclear reactors or particle accelerators. The half lives of these elements show a general trend of decreasing as atomic numbers increase. There are exceptions, however, including several isotopes of curium and dubnium. Some heavier elements in this series, around atomic numbers 110–114, are thought to break the trend and demonstrate increased nuclear stability, comprising the theoretical island of stability.^[1]

Heavy transuranic elements are difficult and expensive to produce, and their prices increase rapidly with atomic number. As of 2008, the cost of weapons-grade plutonium was around $4,000/gram,^[2] and californium exceeded $60,000,000/gram.^[3] Einsteinium is the heaviest element that has been produced in macroscopic quantities.^[4]

Transuranic elements that have not been discovered, or have been discovered but are not yet officially named, use IUPAC's systematic element names. The naming of transuranic elements may be a source of controversy.

Discovery and naming of transuranium elements

So far, essentially all the transuranium elements have been discovered at four laboratories: Lawrence Berkeley National Laboratory in the United States (elements 93–101, 106, and joint credit for 103–105), the Joint Institute for Nuclear Research in Russia (elements 102 and 114–118, and joint credit for 103–105), the GSI Helmholtz Centre for Heavy Ion Research in Germany (elements 107–112), and RIKEN in Japan (element 113).

The Radiation Laboratory (now Lawrence Berkeley National Laboratory) at the University of California, Berkeley, led principally by Edwin McMillan, Glenn Seaborg, and Albert Ghiorso, during 1945-1974:
- 93. neptunium, Np, named after the planet Neptune, as it follows uranium and Neptune follows Uranus in the planetary sequence (1940).
- 94. plutonium, Pu, named after the then-planet Pluto,^{[lower-alpha 1]} following the same naming rule as it follows neptunium and Pluto follows Neptune in the Solar System (1940).
- 95. americium, Am, named because it is an analog to europium, and so was named after the continent where it was first produced (1944).
- 96. curium, Cm, named after Pierre and Marie Curie, famous scientists who separated out the first radioactive elements (1944), as its lighter analog gadolinium was named after Johan Gadolin.
- 97. berkelium, Bk, named after the city of Berkeley, where the University of California, Berkeley is located (1949).
- 98. californium, Cf, named after the state of California, where the university is located (1950).
- 99. einsteinium, Es, named after the theoretical physicist Albert Einstein (1952).
- 100. fermium, Fm, named after Enrico Fermi, the physicist who produced the first controlled chain reaction (1952).
- 101. mendelevium, Md, named after the Russian chemist Dmitri Mendeleev, credited for being the primary creator of the periodic table of the chemical elements (1955).
- 102. nobelium, No, named after Alfred Nobel (1958). This discovery was also claimed by the JINR, which named it joliotium (Jl) after Frédéric Joliot-Curie. IUPAC concluded that the JINR had been the first to convincingly synthesise the element, but retained the name nobelium as deeply entrenched in the literature.
- 103. lawrencium, Lr, named after Ernest O. Lawrence, a physicist best known for development of the cyclotron, and the person for whom the Lawrence Livermore National Laboratory and the Lawrence Berkeley National Laboratory (which hosted the creation of these transuranium elements) are named (1961). This discovery was also claimed by the JINR, which proposed the name rutherfordium (Rf) after Ernest Rutherford. IUPAC concluded that credit should be shared, retaining the name lawrencium as entrenched in the literature.
- 104. rutherfordium, Rf, named after Ernest Rutherford, who was responsible for the concept of the atomic nucleus (1968). This discovery was also claimed by the Joint Institute for Nuclear Research (JINR) in Dubna, Russia (then the Soviet Union), led principally by Georgy Flyorov: they named the element kurchatovium (Ku), after Igor Kurchatov. IUPAC concluded that credit should be shared.
- 105. dubnium, Db, an element that is named after the city of Dubna, where the JINR is located. Originally named "hahnium" (Ha) in honor of Otto Hahn by the Berkeley group (1970) but renamed by the International Union of Pure and Applied Chemistry (1997). This discovery was also claimed by the JINR, which named it nielsbohrium (Ns) after Niels Bohr. IUPAC concluded that credit should be shared.
- 106. seaborgium, Sg, named after Glenn T. Seaborg. This name caused controversy because Seaborg was still alive, but eventually became accepted by international chemists (1974). This discovery was also claimed by the JINR. IUPAC concluded that the Berkeley team had been the first to convincingly synthesise the element.
The Gesellschaft für Schwerionenforschung (Society for Heavy Ion Research) in Darmstadt, Hessen, Germany, led principally by Gottfried Münzenberg, Peter Armbruster, and Sigurd Hofmann, during 1980-2000:
- 107. bohrium, Bh, named after the Danish physicist Niels Bohr, important in the elucidation of the structure of the atom (1981). This discovery was also claimed by the JINR. IUPAC concluded that the GSI had been the first to convincingly synthesise the element. The GSI team had originally proposed nielsbohrium (Ns) to resolve the naming dispute on element 105, but this was changed by IUPAC as there was no precedent for using a scientist's first name in an element name.
- 108. hassium, Hs, named after the Latin form of the name of Hessen, the German Bundesland where this work was performed (1984). This discovery was also claimed by the JINR. IUPAC concluded that the GSI had been the first to convincingly synthesise the element, while acknowledging the pioneering work at the JINR.
- 109. meitnerium, Mt, named after Lise Meitner, an Austrian physicist who was one of the earliest scientists to study nuclear fission (1982).
- 110. darmstadtium, Ds, named after Darmstadt, Germany, the city in which this work was performed (1994). This discovery was also claimed by the JINR, which proposed the name becquerelium after Henri Becquerel, and by the LBNL, which proposed the name hahnium to resolve the dispute on element 105 (despite having protested the reusing of established names for different elements). IUPAC concluded that the GSI had been the first to convincingly synthesize the element.
- 111. roentgenium, Rg, named after Wilhelm Conrad Röntgen, discoverer of X-rays (1994).
- 112. copernicium, Cn, named after astronomer Nicolaus Copernicus (1996).
Rikagaku Kenkyūsho (RIKEN) in Wakō, Saitama, Japan, led principally by Kōsuke Morita:
- 113. nihonium, Nh, named after Japan (Nihon in Japanese) where the element was discovered (2004). This discovery was also claimed by the JINR. IUPAC concluded that RIKEN had been the first to convincingly synthesise the element.
The Joint Institute for Nuclear Research (JINR) in Dubna, Russia, led principally by Yuri Oganessian, in collaboration with several other laboratories including the Lawrence Livermore National Laboratory (LLNL), since 2000:
- 114. flerovium, Fl, named after Soviet physicist Georgy Flyorov, founder of the JINR (1999).
- 115. moscovium, Mc, named after Moscow Oblast, Russia, where the element was discovered (2004).
- 116. livermorium, Lv, named after the Lawrence Livermore National Laboratory, a collaborator with JINR in the discovery (2000).
- 117. tennessine, Ts, named after the region of Tennessee, where the berkelium target needed for the synthesis of the element was manufactured (2010).
- 118. oganesson, Og, named after Yuri Oganessian, who led the JINR team in its discovery of elements 114 to 118 (2002).

Superheavy elements

Superheavy elements, (also known as superheavy atoms, commonly abbreviated SHE) usually refer to the transactinide elements beginning with rutherfordium (atomic number 104). They have only been made artificially, and currently serve no practical purpose because their short half-lives cause them to decay after a very short time, ranging from a few minutes to just a few milliseconds (except for dubnium, which has a half life of over a day), which also makes them extremely hard to study.^[5]^[6]

Superheavy atoms have all been created since the latter half of the 20th century, and are continually being created during the 21st century as technology advances. They are created through the bombardment of elements in a particle accelerator. For example, the nuclear fusion of californium-249 and carbon-12 creates rutherfordium-261. These elements are created in quantities on the atomic scale and no method of mass creation has been found.^[5]

Applications

Transuranium elements may be used to synthesize other superheavy elements.^[7] Elements of the island of stability have potentially important military applications, including the development of compact nuclear weapons.^[8] The potential everyday applications are vast; the element americium is used in devices such as smoke detectors and spectrometers.^[9]^[10]

Related Research Articles

The actinide or actinoid series encompasses the 15 metallic chemical elements with atomic numbers from 89 to 103, actinium through lawrencium. The actinide series derives its name from the first element in the series, actinium. The informal chemical symbol An is used in general discussions of actinide chemistry to refer to any actinide.

<span class="mw-page-title-main">Dubnium</span> Chemical element, symbol Db and atomic number 105

Dubnium is a synthetic chemical element with the symbol Db and atomic number 105. It is highly radioactive: the most stable known isotope, dubnium-268, has a half-life of about 16 hours. This greatly limits extended research on the element.

Hassium is a chemical element with the symbol Hs and the atomic number 108. Hassium is highly radioactive; its most stable known isotopes have half-lives of approximately ten seconds. One of its isotopes, ²⁷⁰Hs, has magic numbers of both protons and neutrons for deformed nuclei, which gives it greater stability against spontaneous fission. Hassium is a superheavy element; it has been produced in a laboratory only in very small quantities by fusing heavy nuclei with lighter ones. Natural occurrences of the element have been hypothesised but never found.

<span class="mw-page-title-main">Nobelium</span> Chemical element, symbol No and atomic number 102

Nobelium is a synthetic chemical element with the symbol No and atomic number 102. It is named in honor of Alfred Nobel, the inventor of dynamite and benefactor of science. A radioactive metal, it is the tenth transuranic element and is the penultimate member of the actinide series. Like all elements with atomic number over 100, nobelium can only be produced in particle accelerators by bombarding lighter elements with charged particles. A total of twelve nobelium isotopes are known to exist; the most stable is ²⁵⁹No with a half-life of 58 minutes, but the shorter-lived ²⁵⁵No is most commonly used in chemistry because it can be produced on a larger scale.

Rutherfordium is a chemical element with the symbol Rf and atomic number 104, named after New Zealand-born British physicist Ernest Rutherford. As a synthetic element, it is not found in nature and can only be made in a particle accelerator. It is radioactive; the most stable known isotope, ²⁶⁷Rf, has a half-life of about 48 minutes.

<span class="mw-page-title-main">Seaborgium</span> Chemical element, symbol Sg and atomic number 106

Seaborgium is a synthetic chemical element with the symbol Sg and atomic number 106. It is named after the American nuclear chemist Glenn T. Seaborg. As a synthetic element, it can be created in a laboratory but is not found in nature. It is also radioactive; the most stable known isotope, ²⁶⁹Sg, has a half-life of approximately 14 minutes.

Livermorium is a synthetic chemical element with the symbol Lv and has an atomic number of 116. It is an extremely radioactive element that has only been created in a laboratory setting and has not been observed in nature. The element is named after the Lawrence Livermore National Laboratory in the United States, which collaborated with the Joint Institute for Nuclear Research (JINR) in Dubna, Russia to discover livermorium during experiments conducted between 2000 and 2006. The name of the laboratory refers to the city of Livermore, California, where it is located, which in turn was named after the rancher and landowner Robert Livermore. The name was adopted by IUPAC on May 30, 2012. Four isotopes of livermorium are known, with mass numbers between 290 and 293 inclusive; the longest-lived among them is livermorium-293 with a half-life of about 60 milliseconds. A fifth possible isotope with mass number 294 has been reported but not yet confirmed.

<span class="mw-page-title-main">Oganesson</span> Chemical element, symbol Og and atomic number 118

Oganesson is a synthetic chemical element with the symbol Og and atomic number 118. It was first synthesized in 2002 at the Joint Institute for Nuclear Research (JINR) in Dubna, near Moscow, Russia, by a joint team of Russian and American scientists. In December 2015, it was recognized as one of four new elements by the Joint Working Party of the international scientific bodies IUPAC and IUPAP. It was formally named on 28 November 2016. The name honors the nuclear physicist Yuri Oganessian, who played a leading role in the discovery of the heaviest elements in the periodic table. It is one of only two elements named after a person who was alive at the time of naming, the other being seaborgium, and the only element whose eponym is alive today.

The names for the chemical elements 104 to 106 were the subject of a major controversy starting in the 1960s, described by some nuclear chemists as the Transfermium Wars because it concerned the elements following fermium on the periodic table.

<span class="mw-page-title-main">Unbinilium</span> Chemical element, symbol Ubn and atomic number 120

Unbinilium, also known as eka-radium or simply element 120, is the hypothetical chemical element in the periodic table with symbol Ubn and atomic number 120. Unbinilium and Ubn are the temporary systematic IUPAC name and symbol, which are used until the element is discovered, confirmed, and a permanent name is decided upon. In the periodic table of the elements, it is expected to be an s-block element, an alkaline earth metal, and the second element in the eighth period. It has attracted attention because of some predictions that it may be in the island of stability.

Moscovium is a synthetic element with the symbol Mc and atomic number 115. It was first synthesized in 2003 by a joint team of Russian and American scientists at the Joint Institute for Nuclear Research (JINR) in Dubna, Russia. In December 2015, it was recognized as one of four new elements by the Joint Working Party of international scientific bodies IUPAC and IUPAP. On 28 November 2016, it was officially named after the Moscow Oblast, in which the JINR is situated.

Tennessine is a synthetic chemical element with the symbol Ts and atomic number 117. It is the second-heaviest known element and the penultimate element of the 7th period of the periodic table.

Copernicium is a synthetic chemical element with the symbol Cn and atomic number 112. Its known isotopes are extremely radioactive, and have only been created in a laboratory. The most stable known isotope, copernicium-285, has a half-life of approximately 30 seconds. Copernicium was first created in 1996 by the GSI Helmholtz Centre for Heavy Ion Research near Darmstadt, Germany. It was named after the astronomer Nicolaus Copernicus.

Nihonium is a synthetic chemical element with the symbol Nh and atomic number 113. It is extremely radioactive; its most stable known isotope, nihonium-286, has a half-life of about 10 seconds. In the periodic table, nihonium is a transactinide element in the p-block. It is a member of period 7 and group 13.

Albert Ghiorso was an American nuclear scientist and co-discoverer of a record 12 chemical elements on the periodic table. His research career spanned six decades, from the early 1940s to the late 1990s.

<span class="mw-page-title-main">Decay chain</span> Series of radioactive decays

In nuclear science, the decay chain refers to a series of radioactive decays of different radioactive decay products as a sequential series of transformations. It is also known as a "radioactive cascade". Most radioisotopes do not decay directly to a stable state, but rather undergo a series of decays until eventually a stable isotope is reached.

A period 7 element is one of the chemical elements in the seventh row of the periodic table of the chemical elements. The periodic table is laid out in rows to illustrate recurring (periodic) trends in the chemical behavior of the elements as their atomic number increases: a new row is begun when chemical behavior begins to repeat, meaning that elements with similar behavior fall into the same vertical columns. The seventh period contains 32 elements, tied for the most with period 6, beginning with francium and ending with oganesson, the heaviest element currently discovered. As a rule, period 7 elements fill their 7s shells first, then their 5f, 6d, and 7p shells in that order, but there are exceptions, such as uranium.

Superheavy elements, also known as transactinide elements, transactinides, or super-heavy elements, are the chemical elements with atomic number greater than 103. The superheavy elements are those beyond the actinides in the periodic table; the last actinide is lawrencium. By definition, superheavy elements are also transuranium elements, i.e., having atomic numbers greater than that of uranium (92). Depending on the definition of group 3 adopted by authors, lawrencium may also be included to complete the 6d series.

Darmstadtium (₁₁₀Ds) is a synthetic element, and thus a standard atomic weight cannot be given. Like all synthetic elements, it has no stable isotopes. The first isotope to be synthesized was ²⁶⁹Ds in 1994. There are 10 known radioisotopes from ²⁶⁷Ds to ²⁸¹Ds and 2 or 3 known isomers. The longest-lived isotope is ²⁸¹Ds with a half-life of 14 seconds.

Unbiquadium, also known as element 124 or eka-uranium, is the hypothetical chemical element with atomic number 124 and placeholder symbol Ubq. Unbiquadium and Ubq are the temporary IUPAC name and symbol, respectively, until the element is discovered, confirmed, and a permanent name is decided upon. In the periodic table, unbiquadium is expected to be a g-block superactinide and the sixth element in the 8th period. Unbiquadium has attracted attention, as it may lie within the island of stability, leading to longer half-lives, especially for ³⁰⁸Ubq which is predicted to have a magic number of neutrons (184).

References

↑ Pluto was a planet at the time of naming, but has since been reclassified as a dwarf planet.

↑ Considine, Glenn, ed. (2002). Van Nostrand's Scientific Encyclopedia (9th ed.). New York: Wiley Interscience. p. 738. ISBN 978-0-471-33230-5.
↑ Morel, Andrew (2008). Elert, Glenn (ed.). "Price of Plutonium". The Physics Factbook. Archived from the original on 20 October 2018.
↑ Martin, Rodger C.; Kos, Steve E. (2001). Applications and Availability of Californium-252 Neutron Sources for Waste Characterization (Report). CiteSeerX 10.1.1.499.1273 .
↑ Silva, Robert J. (2006). "Fermium, Mendelevium, Nobelium and Lawrencium". In Morss, Lester R.; Edelstein, Norman M.; Fuger, Jean (eds.). The Chemistry of the Actinide and Transactinide Elements (Third ed.). Dordrecht, The Netherlands: Springer Science+Business Media. ISBN 978-1-4020-3555-5.
1 2 Heenen, Paul-Henri; Nazarewicz, Witold (2002). "Quest for superheavy nuclei" (PDF). Europhysics News. 33 (1): 5–9. Bibcode:2002ENews..33....5H. doi: 10.1051/epn:2002102 . Archived (PDF) from the original on 20 July 2018.
↑ Greenwood, Norman N. (1997). "Recent developments concerning the discovery of elements 100–111" (PDF). Pure and Applied Chemistry . 69 (1): 179–184. doi:10.1351/pac199769010179. S2CID 98322292. Archived (PDF) from the original on 21 July 2018.
↑ Lougheed, R. W.; et al. (1985). "Search for superheavy elements using ⁴⁸Ca + ²⁵⁴Es^g reaction". Physical Review C . 32 (5): 1760–1763. Bibcode:1985PhRvC..32.1760L. doi:10.1103/PhysRevC.32.1760. PMID 9953034.
↑ Gsponer, André; Hurni, Jean-Pierre (1997). The Physical Principles of Thermonuclear Explosives, Intertial Confinement Fusion, and the Quest for Fourth Generation Nuclear Weapons (PDF). International Network of Engineers and Scientists Against Proliferation. pp. 110–115. ISBN 978-3-933071-02-6. Archived (PDF) from the original on 6 June 2018.
↑ "Smoke Detectors and Americium", Nuclear Issues Briefing Paper, vol. 35, May 2002, archived from the original on 11 September 2002, retrieved 2015-08-26
↑ Nuclear Data Viewer 2.4, NNDC

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