Synthetic element

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  Synthetic elements
  Rare radioactive natural elements; often produced artificially
  Common radioactive natural elements

A synthetic element is one of 24 known chemical elements that do not occur naturally on Earth: they have been created by human manipulation of fundamental particles in a nuclear reactor, a particle accelerator, or the explosion of an atomic bomb; thus, they are called "synthetic", "artificial", or "man-made". The synthetic elements are those with atomic numbers 95–118, as shown in purple on the accompanying periodic table: [1] these 24 elements were first created between 1944 and 2010. The mechanism for the creation of a synthetic element is to force additional protons into the nucleus of an element with an atomic number lower than 95. All known (see: Island of stability) synthetic elements are unstable, but they decay at widely varying rates; the half-lives of their longest-lived isotopes range from microseconds to millions of years.

Contents

Five more elements that were first created artificially are strictly speaking not synthetic because they were later found in nature in trace quantities: 43Tc, 61Pm, 85At, 93Np, and 94Pu, though are sometimes classified as synthetic alongside exclusively artificial elements. [2] The first, technetium, was created in 1937. [3] Plutonium (Pu, atomic number 94), first synthesized in 1940, is another such element. It is the element with the largest number of protons (atomic number) to occur in nature, but it does so in such tiny quantities that it is far more practical to synthesize it. Plutonium is known mainly for its use in atomic bombs and nuclear reactors. [4]

No elements with atomic numbers greater than 99 have any uses outside of scientific research, since they have extremely short half-lives, and thus have never been produced in large quantities.

Properties

All elements with atomic number greater than 94 decay quickly enough into lighter elements such that any atoms of these that may have existed when the Earth formed (about 4.6 billion years ago) have long since decayed. [5] [6] Synthetic elements now present on Earth are the product of atomic bombs or experiments that involve nuclear reactors or particle accelerators, via nuclear fusion or neutron absorption. [7]

Atomic mass for natural elements is based on weighted average abundance of natural isotopes in Earth's crust and atmosphere. For synthetic elements, there is no "natural isotope abundance". Therefore, for synthetic elements the total nucleon count (protons plus neutrons) of the most stable isotope, i.e., the isotope with the longest half-life—is listed in brackets as the atomic mass.

History

Technetium

The first element to be synthesized, rather than discovered in nature, was technetium in 1937. [8] This discovery filled a gap in the periodic table, and the fact that technetium has no stable isotopes explains its natural absence on Earth (and the gap). [9] With the longest-lived isotope of technetium, 97Tc, having a 4.21-million-year half-life, [10] no technetium remains from the formation of the Earth. [11] [12] Only minute traces of technetium occur naturally in Earth's crust—as a product of spontaneous fission of 238U, or from neutron capture in molybdenum—but technetium is present naturally in red giant stars. [13] [14] [15] [16]

Curium

The first entirely synthetic element to be made was curium, synthesized in 1944 by Glenn T. Seaborg, Ralph A. James, and Albert Ghiorso by bombarding plutonium with alpha particles. [17] [18]

Eight others

Synthesis of americium, berkelium, and californium followed soon. Einsteinium and fermium were discovered by a team of scientists led by Albert Ghiorso in 1952 while studying the composition of radioactive debris from the detonation of the first hydrogen bomb. [19] The isotopes synthesized were einsteinium-253, with a half-life of 20.5 days, and fermium-255, with a half-life of about 20 hours. The creation of mendelevium, nobelium, and lawrencium followed.

Rutherfordium and dubnium

During the height of the Cold War, teams from the Soviet Union and the United States independently created rutherfordium and dubnium. The naming and credit for synthesis of these elements remained unresolved for many years, but eventually, shared credit was recognized by IUPAC/IUPAP in 1992. In 1997, IUPAC decided to give dubnium its current name honoring the city of Dubna where the Russian team worked since American-chosen names had already been used for many existing synthetic elements, while the name rutherfordium (chosen by the American team) was accepted for element 104.

The last thirteen

Meanwhile, the American team had created seaborgium, and the next six elements had been created by a German team: bohrium, hassium, meitnerium, darmstadtium, roentgenium, and copernicium. Element 113, nihonium, was created by a Japanese team; the last five known elements, flerovium, moscovium, livermorium, tennessine, and oganesson, were created by Russian–American collaborations and complete the seventh row of the periodic table.

List of synthetic elements

The following elements do not occur naturally on Earth. All are transuranium elements and have atomic numbers of 95 and higher.

Element nameChemical
Symbol		Atomic
Number		First definite
synthesis
Americium Am951944
Curium Cm961944
Berkelium Bk971949
Californium Cf981950
Einsteinium Es991952
Fermium Fm1001952
Mendelevium Md1011955
Nobelium No1021965
Lawrencium Lr1031961
Rutherfordium Rf1041969 (USSR and US) *
Dubnium Db1051970 (USSR and US) *
Seaborgium Sg1061974
Bohrium Bh1071981
Hassium Hs1081984
Meitnerium Mt1091982
Darmstadtium Ds1101994
Roentgenium Rg1111994
Copernicium Cn1121996
Nihonium Nh1132003–04
Flerovium Fl1141999
Moscovium Mc1152003
Livermorium Lv1162000
Tennessine Ts1172009
Oganesson Og1182002
* Shared credit for discovery.

Other elements usually produced through synthesis

All elements with atomic numbers 1 through 94 occur naturally at least in trace quantities, but the following elements are often produced through synthesis.

Element nameChemical
Symbol		Atomic
Number		First definite
discovery		Discovery in nature
Technetium Tc4319371962
Promethium Pm6119451965 [20]
Polonium Po841898
Astatine At8519401943
Francium Fr871939
Radium Ra881898
Actinium Ac891902
Protactinium Pa911913
Neptunium Np9319401952
Plutonium Pu9419401941–42 [21]

Technetium, promethium, astatine, neptunium, and plutonium were discovered through synthesis before being found in nature.

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.

Bohrium is a synthetic chemical element; it has symbol Bh and atomic number 107. It is named after Danish physicist Niels Bohr. As a synthetic element, it can be created in particle accelerators but is not found in nature. All known isotopes of bohrium are highly radioactive; the most stable known isotope is 270Bh with a half-life of approximately 2.4 minutes, though the unconfirmed 278Bh may have a longer half-life of about 11.5 minutes.

A chemical element is a chemical substance that cannot be broken down into other substances by chemical reactions. The basic particle that constitutes a chemical element is the atom. Elements are identified by the number of protons in their nucleus, known as the element's atomic number. For example, oxygen has an atomic number of 8, meaning each oxygen atom has 8 protons in its nucleus. Atoms of the same element can have different numbers of neutrons in their nuclei, known as isotopes of the element. Two or more atoms can combine to form molecules. Chemical compounds are molecules made of atoms of different elements, while mixtures contain atoms of different elements not necessarily combined as molecules. Atoms can be transformed into different elements in nuclear reactions, which change an atom's atomic number.

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.

<span class="mw-page-title-main">Einsteinium</span> Chemical element with atomic number 99 (Es)

Einsteinium is a synthetic chemical element; it has symbol Es and atomic number 99. It is named after Albert Einstein and is a member of the actinide series and is the seventh transuranium element.

Fermium is a synthetic chemical element; it has symbol Fm and atomic number 100. It is an actinide and the heaviest element that can be formed by neutron bombardment of lighter elements, and hence the last element that can be prepared in macroscopic quantities, although pure fermium metal has not yet been prepared. A total of 20 isotopes are known, with 257Fm being the longest-lived with a half-life of 100.5 days.

<span class="mw-page-title-main">Glenn T. Seaborg</span> American chemist (1912–1999)

Glenn Theodore Seaborg was an American chemist whose involvement in the synthesis, discovery and investigation of ten transuranium elements earned him a share of the 1951 Nobel Prize in Chemistry. His work in this area also led to his development of the actinide concept and the arrangement of the actinide series in the periodic table of the elements.

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.

Mendelevium is a synthetic chemical element; it has symbol Md and atomic number 101. A metallic radioactive transuranium element in the actinide series, it is the first element by atomic number that currently cannot be produced in macroscopic quantities by neutron bombardment of lighter elements. It is the third-to-last actinide and the ninth transuranic element and the first transfermium. It can only be produced in particle accelerators by bombarding lighter elements with charged particles. Seventeen isotopes are known; the most stable is 258Md with half-life 51.59 days; however, the shorter-lived 256Md 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.

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

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.

Ununennium, also known as eka-francium or element 119, is a hypothetical chemical element; it has symbol Uue and atomic number 119. Ununennium and Uue are the temporary systematic IUPAC name and symbol respectively, which are used until the element has been 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 alkali metal, and the first element in the eighth period. It is the lightest element that has not yet been synthesized.

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.

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, 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.

<span class="mw-page-title-main">Isotope</span> Different atoms of the same element

Isotopes are distinct nuclear species of the same chemical element. They have the same atomic number and position in the periodic table, but differ in nucleon numbers due to different numbers of neutrons in their nuclei. While all isotopes of a given element have similar chemical properties, they have different atomic masses and physical properties.

Unbihexium, also known as element 126 or eka-plutonium, is a hypothetical chemical element; it has atomic number 126 and placeholder symbol Ubh. Unbihexium and Ubh 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, unbihexium is expected to be a g-block superactinide and the eighth element in the 8th period. Unbihexium has attracted attention among nuclear physicists, especially in early predictions targeting properties of superheavy elements, for 126 may be a magic number of protons near the center of an island of stability, leading to longer half-lives, especially for 310Ubh or 354Ubh which may also have magic numbers of neutrons.

References

  1. ↑ Kulkarni, Mayuri (15 June 2009). "A Complete List of Man-made Synthetic Elements". ScienceStuck. Retrieved 15 May 2019.
  2. ↑ See periodic table here for example.
  3. ↑ "WebElements Periodic Table » Technetium » historical information". www.webelements.com. Webelements. Retrieved 7 November 2019.
  4. ↑ Bradford, Alina (8 December 2016). "Facts About Plutonium". LiveScience. Retrieved 16 May 2019.
  5. ↑ Redd, Nola (November 2016). "How Was Earth Formed?". Space.com. Retrieved 16 May 2019.
  6. ↑ "Synthetic elements". Infoplease. Retrieved 16 May 2019.
  7. ↑ Kulkarni, Mayuri (15 June 2009). "A Complete List of Man-made Synthetic Elements". ScienceStuck. Retrieved 16 May 2019.
  8. ↑ Helmenstine, Anne Marie. "Technetium or Masurium Facts". ThoughtCo. Retrieved 15 May 2019.
  9. ↑ "Technetium decay and its cardiac application". Khan Academy. Retrieved 15 May 2019.
  10. ↑ Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.
  11. ↑ Stewart, Doug. "Technetium Element Facts". Chemicool. Retrieved 15 May 2019.
  12. ↑ Bentor, Yinon. "Periodic Table: Technetium". Chemical Elements. Retrieved 15 May 2019.
  13. ↑ Hammond, C. R. (2004). "The Elements". Handbook of Chemistry and Physics (81st ed.). CRC press. ISBN   978-0-8493-0485-9.
  14. ↑ Moore, C. E. (1951). "Technetium in the Sun". Science. 114 (2951): 59–61. Bibcode:1951Sci...114...59M. doi:10.1126/science.114.2951.59. PMID   17782983.
  15. ↑ Dixon, P.; Curtis, David B.; Musgrave, John; Roensch, Fred; Roach, Jeff; Rokop, Don (1997). "Analysis of Naturally Produced Technetium and Plutonium in Geologic Materials". Analytical Chemistry. 69 (9): 1692–9. doi:10.1021/ac961159q. PMID   21639292.
  16. ↑ Curtis, D.; Fabryka-Martin, June; Dixon, Paul; Cramer, Jan (1999). "Nature's uncommon elements: plutonium and technetium". Geochimica et Cosmochimica Acta. 63 (2): 275. Bibcode:1999GeCoA..63..275C. doi:10.1016/S0016-7037(98)00282-8.
  17. ↑ Krebs, Robert E. The history and use of our earth's chemical elements: a reference guide, Greenwood Publishing Group, 2006, ISBN   0-313-33438-2 p. 322
  18. ↑ Hall, Nina (2000). The New Chemistry: A Showcase for Modern Chemistry and Its Applications . Cambridge University Press. pp.  8–9. ISBN   978-0-521-45224-3.
  19. ↑ Ghiorso, Albert (2003). "Einsteinium and Fermium". Chemical & Engineering News Archive. 81 (36): 174–175. doi:10.1021/cen-v081n036.p174.
  20. ↑ McGill, Ian. "Rare Earth Elements". Ullmann's Encyclopedia of Industrial Chemistry . Vol. 31. Weinheim: Wiley-VCH. p. 188. doi:10.1002/14356007.a22_607. ISBN   978-3527306732.
  21. ↑ Seaborg, Glenn T.; Perlman, Morris L. (1948). "Search for Elements 94 and 93 in Nature. Presence of 94239 in Pitchblende1". Journal of the American Chemical Society. 70 (4). American Chemical Society (ACS): 1571–1573. doi:10.1021/ja01184a083. ISSN   0002-7863.
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