{"id":262,"date":"2020-04-09T10:11:28","date_gmt":"2020-04-09T10:11:28","guid":{"rendered":"https:\/\/thechemicalelements.com\/?page_id=262"},"modified":"2023-08-15T13:50:47","modified_gmt":"2023-08-15T13:50:47","slug":"thorium","status":"publish","type":"post","link":"https:\/\/thechemicalelements.com\/thorium\/","title":{"rendered":"Thorium (Th)"},"content":{"rendered":"\n

Thorium is a chemical element with the atomic number 90 in the periodic table. The average concentration of this substance in the upper crust of Earth amounts to 10.5 ppm, while thorium concentration in the middle layer (the mantle) is around 6.5 ppm. The core (lowest layer) of the Earth\u2019s crust contains 1.2 ppm on average. <\/span><\/p>\n\n\n\n

Being a member of the actinide family of periodic table elements, this naturally occurring radioactive metal has four valence electrons. Its most important use is in nuclear power plants as a nuclear fuel. Due to its radioactivity, thorium is classified as a carcinogen substance.<\/span><\/p>\n\n\n\n

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Chemical and Physical Properties of Thorium<\/span><\/h3>\n\n\n\n
Property<\/strong><\/td>Value<\/strong><\/td><\/tr>
Symbol<\/td>Th<\/td><\/tr>
Atomic number<\/td>90<\/td><\/tr>
Atomic weight (mass)<\/td>232.04 g.mol-1<\/td><\/tr>
Group (number)<\/td>Actinides<\/td><\/tr>
Period<\/td>7 (f-block)<\/td><\/tr>
Color<\/td>A silvery-white lustrous metal<\/td><\/tr>
Physical state<\/td>Solid at 20\u00b0C<\/td><\/tr>
Half-life<\/td>From 1.7(+1.7-0.6) microseconds to 1.405(6)\u00d71010 years<\/td><\/tr>
Electronegativity according to Pauling<\/td>1.3<\/td><\/tr>
Density<\/td>11.7 g.cm-3<\/td><\/tr>
Melting point<\/td>1750\u00b0C, 3182\u00b0F, 2023 K<\/td><\/tr>
Boiling point<\/td>4785\u00b0C, 8645\u00b0F, 5058 K<\/td><\/tr>
Van der Waals radius<\/td>0.182 nm<\/td><\/tr>
Ionic radius<\/td>0.110 nm (+4)<\/td><\/tr>
Isotopes<\/td>31<\/td><\/tr>
Most characteristic isotope<\/td>230Th, 232Th<\/td><\/tr>
Electronic shell<\/td>[Rn] 6d27s2<\/td><\/tr>
The energy of the first ionization<\/td>1107.6 kJ.mol-1<\/td><\/tr>
The energy of the second ionization<\/td>1962.4 kJ.mol-1<\/td><\/tr>
The energy of the third ionization<\/td>2774 kJ.mol-1<\/td><\/tr>
Discovery date<\/td>In 1829 by J\u00f6ns Jacob Berzelius<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Classified in the periodic table under the symbol Th, atomic number 90, atomic mass of 232.04 g.mol<\/span>-1<\/span>, and electron configuration [Rn] 6d<\/span>2<\/span>7s<\/span>2<\/span>, thorium is a silvery-white, soft and ductile, naturally occurring radioactive metal. <\/span><\/p>\n\n\n\n

reaches its boiling point at 4785\u00b0C, 8645\u00b0F, 5058 K, while the melting point is achieved at 1750\u00b0C, 3182\u00b0F, 2023 K. This member of the actinide family of elements in the periodic table has an electronegativity of 1.3 according to Pauling, whereas the atomic radius according to van der Waals is 0.182 nm.<\/span><\/p>\n\n\n\n

Thorium has a dimorphic structure. It changes from face-centered cubic to body-centered cubic at above 1360oC. With a melting point of 3300\u00b0C, thorium oxide melts at the highest temperature among all oxides. Only tungsten<\/a>, tantalum<\/a> carbide, and a few other compounds have a higher melting point than element 90.<\/span><\/p>\n\n\n\n

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How Was Thorium Discovered?<\/span><\/h2>\n\n\n\n

After receiving a mineral sample from Hans Esmark, obtained from an island close to Brevik, Norway, the Swedish chemist J\u00f6ns Jacob Berzelius (1779 – 1848) embarked on studying the unusual black substance that he labeled as <\/span>thorite<\/span><\/i>. <\/span><\/p>\n\n\n\n

After successfully identifying iron<\/a>, manganese<\/a>, lead<\/a>, tin<\/a>, and uranium in the mineral, Berzelius observed another unfamiliar substance. In 1828, the scientist concluded that there is 57.91% of an oxide of the assumed new element contained in the black thorite mineral. Berzelius named this reactive substance <\/span>thorium<\/span><\/i>. <\/span><\/p>\n\n\n\n

Attempting to isolate the elemental form of the new element, Berzelius triggered a chemical reaction. First, he produced thorium chloride by mixing thorium oxide with carbon. In the next step, the discoverer heated it in a stream of chlorine<\/a> gas. After this, Berzelius reacted thorium chloride with potassium<\/a> and got thorium and potassium chloride as a result. <\/span><\/p>\n\n\n\n

In 1898, both the German organic chemist and chemical crystallographer Gerhard Schmidt (1919\u20131971) and the first female scientist to win the Nobel prize Marie Curie (1867\u20131934) independently discovered the radioactive properties of thorium.\u00a0<\/span><\/p>\n\n\n\n

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How Did Thorium Get Its Name?<\/span><\/h2>\n\n\n\n

Thorium is named after <\/span>Thor<\/span><\/a>, the Scandinavian god of thunder, lightning, and war. According to the legend, the Norse God was known for his quick and volatile outbursts of anger, always ready to fight. This relates to the high chemical reactivity and the volatile reactions of element 90.\u00a0<\/span><\/p>\n\n\n\n

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Where Can You Find Thorium?<\/span><\/h2>\n\n\n\n

Element 90 is a naturally occurring radioactive metal. Natural thorium can be found in the soil, rocks, fossil fuels, water, plants, and animals. Thorite and thorianite are minerals in which this radioactive metal mostly occurs. It can also be found in thorium silicate, monazite, etc. The metal allotrope of this chemical element is also found in minerals such as titanite, betafite, gadolinite, and zircon.<\/span><\/p>\n\n\n\n

Thorium is so frequently occurring in nature, that the mining locations rich in this substance can be found all over the Globe, in all continents. However, the largest quantities thorium reserves originate from the mines in Australia, the United States, Russia, Canada, and India. <\/span><\/p>\n\n\n\n

Extraction of thorium as a byproduct of rare-earth elements (REE), as well as isolation of this chemical element from the monazite ore is the most feasible source of thorium production. For commercial purposes, thorium is also obtained by the methods of electrolysis, extraction, and decomposition with sodium<\/a> hydroxide. <\/span><\/p>\n\n\n\n

The world\u2019s first <\/span>thorium molten salt reactor<\/span><\/a> (TMSR) experiment, after the initial experiment at the Oak Ridge National Laboratory (ORNL) during the 1960s, was conducted by the scientists at the Nuclear Research and Consultancy Group (NRG) in Petten, Netherlands. The Salt Irradiation Experiment, or SALIENT, has been prepared in collaboration with the European Commission Laboratory Joint Research Center-ITU, Karlsruhe. Currently, only China, India and Indonesia are included in this <\/span>project<\/span><\/a>.\u00a0<\/span><\/p>\n\n\n\n

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List of Thorium Minerals<\/span><\/h3>\n\n\n\n

The list of minerals from which thorium can be isolated also contains the items:<\/span><\/p>\n\n\n\n