36 Facts About Thorium

Thorium is a weakly radioactive metallic chemical element with the symbol Th and atomic number 90.

Thorium is silvery and tarnishes black when it is exposed to air, forming thorium dioxide; it is moderately soft and malleable and has a high melting point.

Thorium is an electropositive actinide whose chemistry is dominated by the +4 oxidation state; it is quite reactive and can ignite in air when finely divided.

Thorium is estimated to be over three times as abundant as uranium in the Earth's crust, and is chiefly refined from monazite sands as a by-product of extracting rare-earth metals.

Thorium was discovered in 1828 by the Norwegian amateur mineralogist Morten Thrane Esmark and identified by the Swedish chemist Jons Jacob Berzelius, who named it after Thor, the Norse god of thunder.

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Thorium's radioactivity was widely acknowledged during the first decades of the 20th century.

Thorium is still being used as an alloying element in TIG welding electrodes but is slowly being replaced in the field with different compositions.

Thorium is used in strengthening magnesium, coating tungsten wire in electrical equipment, controlling the grain size of tungsten in electric lamps, high-temperature crucibles, and glasses including camera and scientific instrument lenses.

Thorium is a moderately soft, paramagnetic, bright silvery radioactive actinide metal.

Thorium is about as hard as soft steel, so when heated it can be rolled into sheets and pulled into wire.

Thorium is nearly half as dense as uranium and plutonium and is harder than both.

Thorium has a characteristic terrestrial isotopic composition, with atomic weight 232.

Thorium nuclei are susceptible to alpha decay because the strong nuclear force cannot overcome the electromagnetic repulsion between their protons.

Thorium atom has 90 electrons, of which four are valence electrons.

Thorium is much more similar to the transition metals zirconium and hafnium than to cerium in its ionization energies and redox potentials, and hence in its chemistry: this transition-metal-like behaviour is the norm in the first half of the actinide series.

Thorium chemistry is therefore largely that of an electropositive metal forming a single diamagnetic ion with a stable noble-gas configuration, indicating a similarity between thorium and the main group elements of the s-block.

Thorium dioxide is a refractory material, with the highest melting point of any known oxide.

Thorium tetrafluoride has a monoclinic crystal structure like those of zirconium tetrafluoride and hafnium tetrafluoride, where the ions are coordinated with ions in somewhat distorted square antiprisms.

Thorium reacts with hydrogen to form the thorium hydrides and, the latter of which is superconducting below 7.

Thorium is the 41st most abundant element in the Earth's crust.

Thorium only occurs as a minor constituent of most minerals, and was for this reason previously thought to be rare.

Thorium noted impregnated traces of a white mineral, which he cautiously assumed to be an earth of an unknown element.

Thorium was a Norwegian priest and amateur mineralogist who studied the minerals in Telemark, where he served as vicar.

Thorium commonly sent the most interesting specimens, such as this one, to his father, Jens Esmark, a noted mineralogist and professor of mineralogy and geology at the Royal Frederick University in Christiania .

Thorium published his findings in 1829, having isolated an impure sample by reducing with potassium metal.

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Thorium determined that thorium was a very electropositive metal, ahead of cerium and behind zirconium in electropositivity.

Thorium was first observed to be radioactive in 1898, by the German chemist Gerhard Carl Schmidt and later that year, independently, by the Polish-French physicist Marie Curie.

Thorium has been used as a power source on a prototype scale.

Thorium founded a consortium to develop thorium reactors, which included other laboratories: Raytheon Nuclear Inc and Brookhaven National Laboratory in the United States, and the Kurchatov Institute in Russia.

Thorium metal was used in the radiation case of at least one nuclear weapon design deployed by the United States .

Thorium dioxide is used in gas tungsten arc welding to increase the high-temperature strength of tungsten electrodes and improve arc stability.

Thorium oxide is being replaced in this use with other oxides, such as those of zirconium, cerium, and lanthanum.

Thorium dioxide is found in heat-resistant ceramics, such as high-temperature laboratory crucibles, either as the primary ingredient or as an addition to zirconium dioxide.

Thorium dioxide has since been replaced in this application by rare-earth oxides, such as lanthanum, as they provide similar effects and are not radioactive.

Thorium tetrafluoride is used as an anti-reflection material in multilayered optical coatings.

Thorium is more abundant than uranium, and can satisfy world energy demands for longer.