Transuranium element

Last updated October 10, 2024

The transuranium (or transuranic) elements are the chemical elements with atomic number greater than 92, which is the atomic number of uranium. All of them are radioactively unstable and decay into other elements. Except for neptunium and plutonium which have been found in trace amounts in nature, none occur naturally on Earth and they are synthetic.

Overview

Of the elements with atomic numbers 1 to 92, most can be found in nature, having stable isotopes (such as oxygen) 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 technetium, promethium, astatine, and francium; all four occur in nature, but only in very minor branches of the uranium and thorium decay chains, and thus all save francium were first discovered by synthesis in the laboratory rather than in nature.

All elements with higher atomic numbers have been first discovered in the laboratory, with neptunium and plutonium later discovered in nature. They are all radioactive, with a half-life much shorter than the age of the Earth, so any primordial (i.e. present at the Earth's formation) atoms of these elements, 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 by neutron capture in uranium ore with subsequent beta decays (e.g. ²³⁸U + n → ²³⁹U → ²³⁹Np → ²³⁹Pu).

All elements beyond 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]

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.

Discoveries

So far, essentially all transuranium elements have been discovered at four laboratories: Lawrence Berkeley National Laboratory (LBNL) in the United States (elements 93–101, 106, and joint credit for 103–105), the Joint Institute for Nuclear Research (JINR) 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 LBNL) at 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 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, scientists who separated out the first radioactive elements (1944), as its lighter analog gadolinium was named after Johan Gadolin.
- 97. berkelium, Bk, named after Berkeley, where the University of California, Berkeley is located (1949).
- 98. californium, Cf, named after California, where the university is located (1950).
- 99. einsteinium, Es, named after 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 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). The element was originally claimed by a team at the Nobel Institute in Sweden (1957) – though it later became apparent that the Swedish team had not discovered the element, the LBNL team decided to adopt their name nobelium. This discovery was also claimed by JINR, which doubted the LBNL claim, and named the element joliotium (Jl) after Frédéric Joliot-Curie (1965). IUPAC concluded that the JINR had been the first to convincingly synthesize the element (1965), but retained the name nobelium as deeply entrenched in the literature.
- 103. lawrencium, Lr, named after Ernest Lawrence, a physicist best known for development of the cyclotron, and the person for whom Lawrence Livermore National Laboratory and LBNL (which hosted the creation of these transuranium elements) are named (1961). This discovery was also claimed by the JINR (1965), which doubted the LBNL claim and 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 (1969). This discovery was also claimed by JINR, led principally by Georgy Flyorov: they named the element kurchatovium (Ku), after Igor Kurchatov. IUPAC concluded that credit should be shared, and adopted the LBNL name rutherfordium.
- 105. dubnium, Db, an element that is named after Dubna, where JINR is located. Originally named hahnium (Ha) in honor of Otto Hahn by the Berkeley group (1970). This discovery was also claimed by JINR, which named it nielsbohrium (Ns) after Niels Bohr. IUPAC concluded that credit should be shared, and renamed the element dubnium to honour the JINR team.
- 106. seaborgium, Sg, named after Glenn T. Seaborg. This name caused controversy because Seaborg was still alive, but it eventually became accepted by international chemists (1974). This discovery was also claimed by JINR. IUPAC concluded that the Berkeley team had been the first to convincingly synthesize 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 Danish physicist Niels Bohr, important in the elucidation of the structure of the atom (1981). This discovery was also claimed by 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 JINR. IUPAC concluded that the GSI had been the first to convincingly synthesize the element, while acknowledging the pioneering work at 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 JINR, which proposed the name becquerelium after Henri Becquerel, and by 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 GSI had been the first to convincingly synthesize the element.
- 111. roentgenium, Rg, named after Wilhelm Röntgen, discoverer of X-rays (1994).
- 112. copernicium, Cn, named after astronomer Nicolaus Copernicus (1996).
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 JINR. IUPAC concluded that RIKEN had been the first to convincingly synthesize the element.
JINR in Dubna, Russia, led principally by Yuri Oganessian, in collaboration with several other labs including Lawrence Livermore National Laboratory (LLNL), since 2000:
- 114. flerovium, Fl, named after Soviet physicist Georgy Flyorov, founder of JINR (1999).
- 115. moscovium, Mc, named after Moscow Oblast, where the element was discovered (2004).
- 116. livermorium, Lv, named after Lawrence Livermore National Laboratory, a collaborator with JINR in the discovery (2000).
- 117. tennessine, Ts, after Tennessee, where the berkelium target needed for the synthesis of the element was manufactured (2010).
- 118. oganesson, Og, after Yuri Oganessian, who led the JINR team in its discovery of elements 114 to 118 (2002).

Superheavy elements

Superheavy elements, (also known as superheavies, or superheavy atoms, commonly abbreviated SHE) usually refer to the transactinide elements beginning with rutherfordium (atomic number 104). (Lawrencium, the first 6d element, is sometimes but not always included as well.) 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 hours to just milliseconds, which also makes them extremely hard to study.^[5]^[6]

Superheavies 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, in quantities on the atomic scale, and no method of mass creation has been found.^[5]

Applications

Transuranic elements may be used to synthesize 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; americium is used in devices such as smoke detectors and spectrometers.^[9]^[10]

Related Research Articles

The actinide or actinoid series encompasses at least the 14 metallic chemical elements in the 5f series, with atomic numbers from 89 to 102, actinium through nobelium. 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.

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

Lawrencium is a synthetic chemical element; it has symbol Lr and atomic number 103. It is named after Ernest Lawrence, inventor of the cyclotron, a device that was used to discover many artificial radioactive elements. A radioactive metal, lawrencium is the eleventh transuranium element, the third transfermium, and the last member of the actinide series. Like all elements with atomic number over 100, lawrencium can only be produced in particle accelerators by bombarding lighter elements with charged particles. Fourteen isotopes of lawrencium are currently known; the most stable is ²⁶⁶Lr with half-life 11 hours, but the shorter-lived ²⁶⁰Lr is most commonly used in chemistry because it can be produced on a larger scale.

Nobelium is a synthetic chemical element; it has symbol No and atomic number 102. It is named after Alfred Nobel, the inventor of dynamite and benefactor of science. A radioactive metal, it is the tenth transuranium element, the second transfermium, 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 synthetic chemical element; it has symbol Rf and atomic number 104. It is named after 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.

Seaborgium is a synthetic chemical element; it has 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 isotopes have half lives on the order of several minutes.

Livermorium is a synthetic chemical element; it has symbol Lv and atomic number 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. Five isotopes of livermorium are known, with mass numbers of 288 and 290–293 inclusive; the longest-lived among them is livermorium-293 with a half-life of about 80 milliseconds. A sixth possible isotope with mass number 294 has been reported but not yet confirmed.

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.

Unbinilium, also known as eka-radium or element 120, is a hypothetical chemical element; it has 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 chemical element; it has 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; it has symbol Ts and atomic number 117. It has the second-highest atomic number and joint-highest atomic mass of all known elements and is the penultimate element of the 7th period of the periodic table. It is named after the region of Tennessee, where key research institutions involved in its discovery are located.

Copernicium is a synthetic chemical element; it has 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 on his 537th anniversary.

Nihonium is a synthetic chemical element; it has 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.

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.

Unbibium, also known as element 122 or eka-thorium, is a hypothetical chemical element; it has placeholder symbol Ubb and atomic number 122. Unbibium and Ubb are the temporary systematic IUPAC name and symbol respectively, 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 follow unbiunium as the second element of the superactinides and the fourth element of the 8th period. Similarly to unbiunium, it is expected to fall within the range of the island of stability, potentially conferring additional stability on some isotopes, especially ³⁰⁶Ubb which is expected to have a magic number of neutrons (184).

Superheavy elements, also known as transactinide elements, transactinides, or super-heavy elements, or superheavies for short, are the chemical elements with atomic number greater than 104. 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.

Unbiunium, also known as eka-actinium or element 121, is a hypothetical chemical element; it has symbol Ubu and atomic number 121. Unbiunium and Ubu are the temporary systematic IUPAC name and symbol respectively, 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 the first of the superactinides, and the third element in the eighth period. It has attracted attention because of some predictions that it may be in the island of stability. It is also likely to be the first of a new g-block of elements.

Unbiquadium, also known as element 124 or eka-uranium, is a hypothetical chemical element; it has placeholder symbol Ubq and atomic number 124. 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.

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↑ 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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