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  Synthetic elements
  Rare radioactive natural elements; often produced artificially

A synthetic element is one of twenty-four chemical elements that do not occur naturally on Earth:[1] they have been created by human manipulation of fundamental particles in a nuclear reactor or particle accelerator, or detonation of an atomic bomb; and thus are called "synthetic", "artificial", or "man-made".[2] The synthetic elements are those with atomic numbers 95–118:[3] the twenty-four were created between 1944 and 2010. The mechanism for the creation of a synthetic element is to force additional protons onto the nucleus of an element with an atomic number lower than ninety-five. All synthetic elements are unstable, but they decay at at a widely varying rate: their half-lives range from 15.6 million years to a few hundred microseconds.

Plutonium, atomic number 94, first synthesized in 1940, is extremely well-known due to its use in atomic bombs and nuclear reactors.[4] No elements with an atomic number 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.

Seven other elements that were created artificially - and thus initially considered to be synthetic - were later discovered to exist in nature in trace quantities. The first, technetium, was created in 1937.

Contents

PropertiesEdit

Any elements with atomic number 94-118 present at the formation of the earth about 4.6 billion years ago have decayed sufficiently rapidly into lighter elements relative to the age of Earth that any atoms of these elements that may have existed when the Earth formed have long since decayed.[5][6] Atoms of 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 that occur in Earth's crust and atmosphere. For synthetic elements, the isotope depends on the means of synthesis, so the concept of natural isotope abundance has no meaning. 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.

HistoryEdit

TechnetiumEdit

The first element discovered through synthesis was technetium—its discovery being definitely confirmed in 1937.[8] This discovery filled a gap in the periodic table, and the fact that no stable isotopes of technetium exist 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 the Earth's crust—as a spontaneous fission product of uranium-238 or by neutron capture in molybdenum ores—but technetium is present naturally in red giant stars.[13][14][15][16]

CuriumEdit

The first discovered purely synthetic element was curium, synthesized in 1944 by Glenn T. Seaborg, Ralph A. James, and Albert Ghiorso by bombarding plutonium with alpha particles.[17][18][19][20]

Eight othersEdit

The discoveries 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 radioactive debris from the detonation of the first hydrogen bomb.[21] The isotopes discovered were einsteinium-253, with a half-life of 20.5 days, and fermium-255, with a half-life of about 20 hours. The discoveries of mendelevium, nobelium, and lawrencium followed.

Rutherfordium and dubniumEdit

During the height of the Cold War, teams from the Soviet Union and the United States independently discovered rutherfordium and dubnium. The naming and credit for discovery 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 made their discoveries 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 twelveEdit

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

List of synthetic elementsEdit

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

Element name Chemical
Symbol
Atomic
Number
First definite
synthesis
Americium Am 95 1944
Curium Cm 96 1944
Berkelium Bk 97 1949
Californium Cf 98 1950
Einsteinium Es 99 1952
Fermium Fm 100 1952
Mendelevium Md 101 1955
Nobelium No 102 1966
Lawrencium Lr 103 1971
Rutherfordium Rf 104 1966 (USSR), 1969 (US) *
Dubnium Db 105 1968 (USSR), 1970 (US) *
Seaborgium Sg 106 1974
Bohrium Bh 107 1981
Hassium Hs 108 1984
Meitnerium Mt 109 1982
Darmstadtium Ds 110 1994
Roentgenium Rg 111 1994
Copernicium Cn 112 1996
Nihonium Nh 113 2003–4
Flerovium Fl 114 1999
Moscovium Mc 115 2003
Livermorium Lv 116 2000
Tennessine Ts 117 2010
Oganesson Og 118 2002
* Shared credit for discovery.

Other elements usually produced through synthesisEdit

All elements with atomic numbers 1 through 94 occur naturally at least in trace quantities, but the following elements are often produced through synthesis. Technetium, promethium, astatine, neptunium, and plutonium were discovered through synthesis before being found in nature.

Element name Chemical
Symbol
Atomic
Number
First definite
discovery
Technetium Tc 43 1937
Promethium Pm 61 1945
Polonium Po 84 1898
Astatine At 85 1940
Francium Fr 87 1939
Actinium Ac 89 1902
Protactinium Pa 91 1913
Neptunium Np 93 1940
Plutonium Pu 94 1940

ReferencesEdit

  1. ^ Kulkarni, Mayuri. "A Complete List of Man-made Synthetic Elements". ScienceStuck. Retrieved 15 May 2019.
  2. ^ Kulkarni, Mayuri. "A Complete List of Man-made Synthetic Elements". ScienceStuck. Retrieved 15 May 2019.
  3. ^ Kulkarni, Mayuri. "A Complete List of Man-made Synthetic Elements". ScienceStuck. Retrieved 15 May 2019.
  4. ^ Bradford, Alina. "Facts About Plutonium". LiveSci=nce. Retrieved 16 May 2019.
  5. ^ Redd, Nola. "How Was Earth Formed?". Space.com. Retrieved 16 May 2019.
  6. ^ "Synthetic elements". Infoplease. Retrieved 16 May 2019.
  7. ^ Kulkarni, Mayuri. "A Complete List of Man-made Synthetic Elements". ScienceStuck. Retrieved 16 May 2019.
  8. ^ Helmenstine, Anne Marie. "Technetium or Masurium Facts". ThoughtCo. ThoughtCo. Retrieved 15 May 2019.
  9. ^ "Technetium decay and its cardiac application". KhanAcademy. Khan Academy. Retrieved 15 May 2019.
  10. ^ Audi, Georges; Kondev, Filip G.; Wang, Meng; Huang, Wen Jia; Naimi, Sarah (2017), "The NUBASE2016 evaluation of nuclear properties" (PDF), Chinese Physics C, 41 (3): 030001–1—030001–138, Bibcode:2017ChPhC..41c0001A, doi:10.1088/1674-1137/41/3/030001
  11. ^ Stewart, Doug. "Technetium Element Facts". Chemicool. Retrieved 15 May 2019.
  12. ^ Yinon, 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. ^ Harper, Douglas. "pandemonium". Online Etymology Dictionary.
  19. ^ Harper, Douglas. "delirium". Online Etymology Dictionary.
  20. ^ 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.
  21. ^ Ghiorso, Albert (2003). "Einsteinium and Fermium". Chemical and Engineering News. 81 (36): 174–175. doi:10.1021/cen-v081n036.p174.

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