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Thorium

A weakly radioactive actinide metal used in nuclear and industrial applications.

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A radioactive actinide metal, thorium is bright silvery, moderately soft, and paramagnetic, and can be bent or shaped.[1] Jöns Jacob Berzelius, a Swedish chemist, first identified thorium in 1828 while analyzing a mineral from Norway, naming it after the Norse deity Thor.[2] Thorium serves as an alloying component in TIG welding electrodes, though it is gradually being replaced, and it has been proposed as a substitute for uranium fuel in nuclear reactors, with several such reactors already constructed.[3]

Quick Facts

Atomic number
90
Discovered by
Jöns Jacob Berzelius
Year of discovery
1828
Crustal abundance
8.1 g/tonne

Facts from the source article.

Key facts and history

In 1815, Berzelius analysed a gadolinite sample from Falun, Sweden, and privately named a putative element "thorium" in 1817, but retracted his findings in 1824 when the mineral proved to be mostly yttrium orthophosphate.[4] In 1828, Morten Thrane Esmark found a black mineral on Løvøya island in Norway, which his father sent to Berzelius for examination.[5] Berzelius determined it contained a new element, published his findings in 1829, and reused the name thorium for the source mineral thorite.[6] Thorium has a melting point of 1750 °C, the highest among actinides up to californium.[1][7]

The only isotope of thorium occurring in quantity in nature is 232 Th, with a half-life of 14.0 billion years.[8] Thorium is the 37th most abundant element in the Earth's crust, with an abundance of 12 parts per million.[9] Monazite is the most important commercial source of thorium, containing around 2.5% thorium on average.[10] When pure, thorium is very ductile and can undergo cold-rolling, swaging, and drawing, which are typical metalworking processes.[1]

References

  1. Wikipedia, "Thorium" (CC BY-SA 4.0), which cites: Wickleder Fourest Dorhout 2006, p. 61–63; Wickleder Fourest Dorhout 2006, p. 61–63 (original not read by us) en.wikipedia.org
  2. Wikipedia, "Thorium" (CC BY-SA 4.0), which cites: Marshall, James L., and Virginia R. Marshall. "Rediscovery of the Elements: Thorium—Løvøya, Langesundsfjord, Norway." The Hexagon, vol. 93, no. 1, 2001, pp. 4-6 (original not read by us) en.wikipedia.org
  3. Wikipedia, "Thorium" (CC BY-SA 4.0), which cites: Negre, "Reversed flow of Atlantic deep water during the Last Glacial Maximum", Nature, 2010, p. 84–8 (original not read by us) en.wikipedia.org
  4. Wikipedia, "Thorium" (CC BY-SA 4.0), which cites: Fontani, "The Lost Elements: The Periodic Table's Shadow Side", Oxford University Press, 2014, p. 73; Ryabchikov, "The Analytical Chemistry of Thorium: International Series of Monographs on Analytical Chemistry", Elsevier, 2013, p. 1; Thomson, "A System of Chemistry of Inorganic Bodies", Baldwin & Cradock and William Blackwood, 1831, p. 475; Wickleder Fourest Dorhout 2006, p. 61–63; Fontani, "The Lost Elements: The Periodic Table's Shadow Side", Oxford University Press, 2014, p. 73; Berzelius, "Undersökning af några Mineralier. 1. Phosphorsyrad en.wikipedia.org
  5. Wikipedia, "Thorium" (CC BY-SA 4.0), which cites: Selbekk, "Morten Thrane Esmark", Kunnskapsforlaget, 2007 (original not read by us) en.wikipedia.org
  6. Wikipedia, "Thorium" (CC BY-SA 4.0), which cites: Wickleder Fourest Dorhout 2006, p. 61–63; Weeks, "The discovery of the elements. XI. Some elements isolated with the aid of potassium and sodium: Zirconium, titanium, cerium, and thorium", Journal of Chemical Education, 1932, p. 1231; Berzelius, "Untersuchung eines neues Minerals und einer darin erhalten zuvor unbekannten Erde", Annalen der Physik und Chemie, 1829, p. 385–415; Berzelius, "Undersökning af ett nytt mineral (Thorit), som innehåller en förut obekant jord", Kungliga Svenska Vetenskaps Akademiens Handlingar, 1829, p. 1–30; Weeks, "Th en.wikipedia.org
  7. Wikipedia, "Thorium" (CC BY-SA 4.0), which cites: Johansson, "Anomalous fcc crystal structure of thorium metal.", Physical Review Letters, 1995, p. 280–283; Johansson, "Anomalous fcc crystal structure of thorium metal.", Physical Review Letters, 1995, p. 280–283 (original not read by us) en.wikipedia.org
  8. Wikipedia, "Thorium" (CC BY-SA 4.0) en.wikipedia.org
  9. Wikipedia, "Thorium" (CC BY-SA 4.0), which cites: Wickleder Fourest Dorhout 2006, p. 61–63; Agency for Toxic Substances and Disease Registry, "Thorium", 2016; Emsley, "Nature's Building Blocks: An A-Z Guide to the Elements", Oxford University Press, 25 August 2011; Wickleder Fourest Dorhout 2006, p. 61–63; Woodhead, "The metamictization of zircon: Radiation dose-dependent structural characteristics", American Mineralogist, 1 February 1991, p. 74–82; Szymanski, "A mineralogical study and crystal-structure determination of nonmetamict ekanite, ThCa<sub>2</sub>Si<sub>8</sub>O<sub>20</sub>", The C en.wikipedia.org
  10. Wikipedia, "Thorium" (CC BY-SA 4.0), which cites: Wickleder Fourest Dorhout 2006, p. 61–63; Greenwood Earnshaw 1997, p. 1262; Wickleder Fourest Dorhout 2006, p. 61–63; Wickleder Fourest Dorhout 2006, p. 61–63 (original not read by us) en.wikipedia.org

Each numbered sentence above was checked against the source it cites before publication. Sentences citing Wikipedia adapt text from the English Wikipedia article Thorium (contributors), used under CC BY-SA 4.0; this entry is available under the same licence. Other sources were used for facts only; no text or images are copied from them.

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Thorium · Chemical Elements

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