Synthetic element

Short description: Chemical elements that do not occur naturally

Synthetic elements

Rare radioactive natural elements; often produced artificially

Common radioactive natural elements

A synthetic element is a known chemical element that does not occur naturally on Earth: it has been created by human manipulation of fundamental particles in a nuclear reactor, a particle accelerator, or the explosion of an atomic bomb; thus, it is 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.

Five more elements that were first created artificially are strictly speaking not synthetic because they were later found in nature in trace quantities: technetium (43Tc), promethium (61Pm), astatine (85At), neptunium (93Np), and plutonium (94Pu); although they are sometimes classified as synthetic alongside exclusively artificial elements.[2] The first, technetium, was created in 1937.[3] Plutonium, 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.

## Contents

* 1 Properties
* 1.1 Half-lifes
* 2 History
* 2.1 Technetium
* 2.2 Curium
* 2.3 Eight others
* 2.4 Rutherfordium and dubnium
* 2.5 The last thirteen
* 3 List of synthetic elements
* 4 Other elements usually produced through synthesis
* 5 References
* 6 External links

## 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.

### Half-lifes

The list below shows (total half-life) most time first for some of the elements most stable isotopes:

* (Cm, Z=96): Curium-247, 1.64 × 107 years [8] / 1.56 [9]
* (Am, Z=95): Americium-243; 7,370 years [10][9]
* (Bk, Z=97): Berkelium-247; 1.4 × 103 [11] / 1380 [9][12]
* (Cf, Z=98): Californium-251; 898 [9] / 252; approximately 800 [13]
* (Es, Z=99): Einsteinium-252; 471.7 days [9]
* (Fm, Z=100): Fermium-257; 100.5 [9]
* (Md, Z=101): Mendelevium-258; 51.5 [9]
* (Lr, Z=103): Lawrencium-262; 3.6 hours [9] = 216 minutes [14]
* (No, Z=102): Nobelium-259; 58 minutes [14]
* (Rf, Z=104): Rutherfordium-263; approximately 10 [9]
* (Sg, Z=106): Seaborgium-269; 5 ± 2 [15]
* (Bh, Z=107): Bohrium-270; approximately 61 seconds [16]

## History

### Technetium

The first element to be synthesized, rather than discovered in nature, was technetium in 1937.[17] 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).[18] With the longest-lived isotope of technetium, 97Tc, having a 4.21-million-year half-life,[19] no technetium remains from the formation of the Earth.[20][21] 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.[22][23][24][25]

### 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.[26][27]

### 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.[28] 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 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 | 1965
Lawrencium | Lr | 103 | 1961
Rutherfordium | Rf | 104 | 1969 (USSR and US) *
Dubnium | Db | 105 | 1970 (USSR and 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 | 2003–04
Flerovium | Fl | 114 | 1999
Moscovium | Mc | 115 | 2003
Livermorium | Lv | 116 | 2000
Tennessine | Ts | 117 | 2009
Oganesson | Og | 118 | 2002
* 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 name | Chemical
symbol | Atomic
number | First definite
discovery | Discovery
in nature

|
|
|
|

Technetium‡ | Tc | 43 | 1937 | 1962
Promethium‡ | Pm | 61 | 1945 | 1965[29]
Polonium | Po | 84 | 1898 |
Astatine‡ | At | 85 | 1940 | 1943
Francium | Fr | 87 | 1939 |
Radium | Ra | 88 | 1898 |
Actinium | Ac | 89 | 1902 |
Protactinium | Pa | 91 | 1913 |
Neptunium‡ | Np | 93 | 1940 | 1952
Plutonium‡ | Pu | 94 | 1940 | 1941–42[30]

‡ These five elements were discovered through synthesis before being found in nature.

## References

1. ↑ Kulkarni, Mayuri (15 June 2009). "A Complete List of Man-made Synthetic Elements". https://sciencestruck.com/synthetic-elements.
2. ↑ See periodic table here for example.
3. ↑ "WebElements Periodic Table » Technetium » historical information". Webelements. https://www.webelements.com/technetium/history.html.
4. ↑ Bradford, Alina (8 December 2016). "Facts About Plutonium". https://www.livescience.com/39871-facts-about-plutonium.html.
5. ↑ Redd, Nola (November 2016). "How Was Earth Formed?". https://www.space.com/19175-how-was-earth-formed.html.
6. ↑ "Synthetic elements". https://www.infoplease.com/encyclopedia/science/chemistry/elements/synthetic-elements.
7. ↑ Kulkarni, Mayuri (15 June 2009). "A Complete List of Man-made Synthetic Elements". https://sciencestruck.com/synthetic-elements.
8. ↑ John Daintith, ed. "curium". A Dictionary of Chemistry (6 ed.). Oxford University Press. doi:10.1093/acref/9780199204632.001.0001. https://www.oxfordreference.com/display/10.1093/oi/authority.20110803095654122.
9. ↑ 9.0 9.1 9.2 9.3 9.4 9.5 9.6 9.7 9.8 Giora Shaviv (2012). "Chapter 13 A Process in Search of an Environment: The r-process". The Synthesis of the Elements The Astrophysical Quest for Nucleosynthesis and What It Can Tell Us About the Universe. Technion-Israel Institute of Technology: Springer-Verlag. p. 549. doi:10.1007/978-3-642-28385-7. ISBN 9783642283857. https://www.google.co.uk/books/edition/The_Synthesis_of_the_Elements/sXdQuJddBpYC?hl=en&gbpv=1&dq=Einsteinium-252;+471.7&pg=PA549&printsec=frontcover. "Values taken from Ehmann, W.D. J.Chem. Ed. 38, 53 (1961)"
10. ↑ John Emsley (1 September 2008). "education in chemistry Americium". University of Cambridge: Royal Society of Chemistry. https://edu.rsc.org/elements/americium/2020001.article.
11. ↑ "berkelium". A Dictionary of Physics (6 ed.). Oxford University Press. 2009. doi:10.1093/acref/9780199233991.001.0001. https://www.oxfordreference.com/display/10.1093/oi/authority.20110803095500708.
12. ↑ Paul Alexandre (2020). "Appendix A". Isotopes and the Natural Environment. Brandon University, Canada: Springer Nature Switzerland AG. p. 89. doi:10.1007/978-3-030-33652-3. ISBN 9783030336523. https://www.google.co.uk/books/edition/Isotopes_and_the_Natural_Environment/kqbMDwAAQBAJ?hl=en&gbpv=1&dq=:+Rutherfordium-263+approximately+10&pg=PA89&printsec=frontcover.
13. ↑ "More about Californium". Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge. https://www.ccdc.cam.ac.uk/elements/californium/.
14. ↑ 14.0 14.1 John Emsley (2003). "The Transfermium Elements". Nature's Building Blocks An A-Z Guide to the Elements. University of Cambridge: Oxford University Press. p. 458. ISBN 9780198503408. https://www.google.co.uk/books/edition/Nature_s_Building_Blocks/j-Xu07p3cKwC?hl=en&gbpv=1&dq=Nobelium-259;+58+minutes&pg=PA458&printsec=frontcover.
15. ↑ "Periodic Table Seaborgium". pubchem.ncbi.nlm.nih.gov. https://pubchem.ncbi.nlm.nih.gov/element/Seaborgium#section=Atomic-Mass-Half-Life-and-Decay.
16. ↑ Camille L. Franicevich. "Isotopes of Bohrium". ISOFLEX, San Francisco, CA. https://www.isoflex.com/bohrium-bh.
17. ↑ Helmenstine, Anne Marie. "Technetium or Masurium Facts". ThoughtCo. https://www.thoughtco.com/technetium-or-masurium-facts-606601.
18. ↑ "Technetium decay and its cardiac application". Khan Academy. https://www.khanacademy.org/test-prep/mcat/physical-sciences-practice/physical-sciences-practice-tut/e/cs-passage-4.
19. ↑ Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties". Chinese Physics C 45 (3). doi:10.1088/1674-1137/abddae. https://www-nds.iaea.org/amdc/ame2020/NUBASE2020.pdf.
20. ↑ Stewart, Doug. "Technetium Element Facts". https://www.chemicool.com/elements/technetium.html.
21. ↑ Bentor, Yinon. "Periodic Table: Technetium". http://www.chemicalelements.com/elements/tc.html.
22. ↑ Hammond, C. R. (2004). "The Elements". Handbook of Chemistry and Physics (81st ed.). CRC press. ISBN 978-0-8493-0485-9. https://archive.org/details/crchandbookofche81lide.
23. ↑ Moore, C. E. (1951). "Technetium in the Sun". Science 114 (2951): 59–61. doi:10.1126/science.114.2951.59. PMID 17782983. Bibcode: 1951Sci...114...59M.
24. ↑ 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.
25. ↑ Curtis, D.; Fabryka-Martin, June; Dixon, Paul; Cramer, Jan (1999). "Nature's uncommon elements: plutonium and technetium". Geochimica et Cosmochimica Acta 63 (2): 275. doi:10.1016/S0016-7037(98)00282-8. Bibcode: 1999GeCoA..63..275C. https://digital.library.unt.edu/ark:/67531/metadc704244/.
26. ↑ 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
27. ↑ 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. https://archive.org/details/newchemistry00hall.
28. ↑ Ghiorso, Albert (2003). "Einsteinium and Fermium". Chemical & Engineering News Archive 81 (36): 174–175. doi:10.1021/cen-v081n036.p174.
29. ↑ McGill, Ian. "Ullmann's Encyclopedia of Industrial Chemistry". Ullmann's Encyclopedia of Industrial Chemistry. 31. Weinheim: Wiley-VCH. p. 188. doi:10.1002/14356007.a22_607.
30. ↑ 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 (American Chemical Society (ACS)) 70 (4): 1571–1573. doi:10.1021/ja01184a083. ISSN 0002-7863.

## External links

* "einsteinium (Es) - chemical element". http://www.britannica.com/EBchecked/topic/181416/einsteinium-Es.
* "mendelevium (Md) - chemical element". http://www.britannica.com/EBchecked/topic/374759/mendelevium-Md.
* "synthetic elements". http://encyclopedia2.thefreedictionary.com/synthetic+elements.
* "It's Elemental - The Element Fermium". http://education.jlab.org/itselemental/ele100.html.
* Kulkarni, Mayuri (15 June 2009). "A Complete List of Man-made Synthetic Elements". https://sciencestruck.com/synthetic-elements.

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