Thorium

Extracted Attributes

• Symbol

  Th

• Isotopes

  All known isotopes are unstable

• Appearance

  Light silver metal, tarnishes olive-grey or black in air

• Reactivity

  Quite reactive, can ignite in air when finely divided

• Atomic Number

  90

• Boiling Point

  about 4000 °C (7200 °F)

• Melting Point

  about 1700 °C (3100 °F)

• Radioactivity

  Weakly radioactive

• Classification

  Primordial element, Electropositive actinide

• China's Reserves

  Vast

• Specific Gravity

  about 11.66 (at 17 °C)

• Half-life of 232Th

  14.05 billion years

• Most Stable Isotope

  232Th

• Dominant Oxidation State

  +4

• Primary Extraction Source

  Monazite sands (by-product of rare-earth element mining)

• Abundance in Earth's Crust

  Over three times more abundant than uranium (average 10.5 ppm)

• State at Normal Conditions

  Solid

• Health Classification (DHHS)

  Reasonably anticipated to be a human carcinogen

Timeline

• Thorium was discovered by the Swedish chemist Jöns Jacob Berzelius. (Source: Summary, Wikipedia, Web Search)

  1828-XX-XX

• The radioactivity of thorium was independently found by German chemist Gerhard Carl Schmidt and French physicist Marie Curie. (Source: Britannica)

  1898-XX-XX

• First applications of thorium were developed in the late 19th century. (Source: Summary, Wikipedia)

  18XX-XX-XX

• Thorium's radioactivity was widely acknowledged during the first decades of the 20th century. (Source: Summary, Wikipedia)

  19XX-XX-XX

• A solution of thorium was given to people for special X-ray tests (until 1955). (Source: Web Search (CDC))

  1928-XX-XX

• In the second half of the 20th century, thorium was replaced in many uses due to concerns about its radioactive properties. (Source: Summary, Wikipedia)

  1950-XX-XX

• China discovered a vast thorium reserve and is operating an advanced Molten Salt Reactor. (Source: Related Documents)

  20XX-XX-XX

Thorium

Thorium is a chemical element; it has symbol Th and atomic number 90. Thorium is a weakly radioactive light silver metal which tarnishes olive grey when it is exposed to air, forming thorium dioxide; it is moderately soft, 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. All known thorium isotopes are unstable. The most stable isotope, 232Th, has a half-life of 14.05 billion years, or about the age of the universe; it decays very slowly via alpha decay, starting a decay chain named the thorium series that ends at stable 208Pb. On Earth, thorium and uranium are the only elements with no stable or nearly-stable isotopes that still occur naturally in large quantities as primordial elements. 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 elements. Thorium was discovered in 1828 by the Swedish chemist Jöns Jacob Berzelius, who named it after Thor, the Norse god of thunder and war. Its first applications were developed in the late 19th century. Thorium's radioactivity was widely acknowledged during the first decades of the 20th century. In the second half of the 20th century, thorium was replaced in many uses due to concerns about its radioactive properties. Thorium is still used as an alloying element in TIG welding electrodes but is slowly being replaced in the field with different compositions. It was also material in high-end optics and scientific instrumentation, used in some broadcast vacuum tubes, and as the light source in gas mantles, but these uses have become marginal. It has been suggested as a replacement for uranium as nuclear fuel in nuclear reactors, and several thorium reactors have been built. Thorium is also used in strengthening magnesium, coating tungsten wire in electrical and welding equipment, controlling the grain size of tungsten in electric lamps, high-temperature crucibles, and glasses including camera and scientific instrument lenses. Other uses for thorium include heat-resistant ceramics, aircraft engines, and in light bulbs. Ocean science has utilised 231Pa/230Th isotope ratios to understand the ancient ocean.

Web Search Results

• Thorium - World Nuclear Association

  Thorium is a naturally-occurring, slightly radioactive metal discovered in 1828 by the Swedish chemist Jons Jakob Berzelius, who named it after Thor, the Norse god of thunder. It is found in small amounts in most rocks and soils, where it is about three times more abundant than uranium. Soil contains an average of around 6 parts per million (ppm) of thorium. Thorium is very insoluble, which is why it is plentiful in sands but not in seawater, in contrast to uranium. [...] When pure, thorium is a silvery white metal that retains its lustre for several months. However, when it is contaminated with the oxide, thorium slowly tarnishes in air, becoming grey and eventually black. When heated in air, thorium metal ignites and burns brilliantly with a white light. Thorium oxide (ThO2), also called thoria, has one of the highest melting points of all oxides (3300°C) and so it has found applications in light bulb elements, lantern mantles, arc-light lamps, welding [...] Thorium exists in nature in a single isotopic form – Th-232 – which decays very slowly (its half-life is about three times the age of the Earth). The decay chains of natural thorium and uranium give rise to minute traces of Th-228, Th-230 and Th-234, but the presence of these in mass terms is negligible. It decays eventually to lead-208.

• Thorium's Long-Term Potential in Nuclear Energy: New IAEA Analysis

  Thorium is a silvery, slightly radioactive metal commonly found in igneous rocks and heavy mineral sands. It was named after Thor, the god of thunder in Norse mythology. It is three to four times more abundant in nature than uranium but historically has found little use in industry or power generation. This is partly because thorium in itself is not a nuclear fuel, but it can be used to create one. Thorium-232, the only naturally occurring isotope of thorium, is a fissionable material but not a [...] ## What can thorium offer? Thorium boasts several advantages over the conventional nuclear fuel, uranium-235. Thorium can generate more fissile material (uranium-233) than it consumes while fuelling a water-cooled%20are,directly%20in%20the%20steam%20turbine.) or molten-salt reactor. According to estimates, the Earth's upper crust contains an average of 10.5 parts per million (ppm) of thorium, compared with about 3 ppm of uranium.

• Thorium | Description, Properties, & Uses - Britannica

  thorium (Th), radioactive chemical element of the actinoid series of the periodic table, atomic number 90; it is a useful nuclear reactor fuel. Thorium was discovered (1828) by Swedish chemist Jöns Jacob Berzelius. It is silvery white but turns gray or black on exposure to air. It is about half as abundant as lead and is three times more abundant than uranium in Earth’s crust. Thorium is commercially recovered from the mineral monazite and occurs also in other minerals such as thorite and [...] The radioactivity of thorium was found independently (1898) by German chemist Gerhard Carl Schmidt and by French physicist Marie Curie. Natural thorium is a mixture of radioactive isotopes, predominantly the very long-lived thorium-232 (1.40 × 1010-year half-life), the parent of the thorium radioactive decay series. Other isotopes occur naturally in the uranium and actinium decay series, and thorium is present in all uranium ores. Thorium-232 is useful in breeder reactors because on capturing [...] | | | | --- | --- | | atomic number | 90 | | atomic weight | 232.038 | | melting point | about 1,700 °C (3,100 °F) | | boiling point | about 4,000 °C (7,200 °F) | | specific gravity | about 11.66 (17 °C) | | oxidation state | +4 | | electron configuration of gaseous atomic state | [Rn]6d27s2 |

• Radionuclide Basics: Thorium | US EPA

  Thorium (chemical symbol Th) is a naturally occurring radioactive metal found at trace levels in soil, rocks, water, plants and animals. Thorium is solid under normal conditions. There are natural and man-made forms of thorium, all of which are radioactive. In general, naturally occurring thorium exists as Th-232, Th-230 or Th-228. ## Thorium in the Environment [...] ## Thorium Sources Thorium is used to make ceramics, welding rods, camera and telescope lenses, fire brick, heat resistant paint and metals used in the aerospace industry, as well as in nuclear reactions. Thorium has the potential to be used as a fuel for generating nuclear energy. Since thorium is naturally present in the environment, people are exposed to tiny amounts in air, food and water. The amounts are usually very small and pose little health hazard. [...] Natural thorium is present in trace quantities in virtually all rock, soil, water, plants and animals. Where higher concentrations occur in rock or sands, thorium may be mined and refined, producing waste products such as mill tailings. If not properly controlled, wind and water can introduce the tailings into the wider environment. Commercial and federal facilities that have processed thorium may also have released thorium to the air, water or soil. Man-made thorium isotopesisotopesA form of

• Thorium | ToxFAQs™ | ATSDR - CDC

  ### ToxFAQs™ for Thorium Spanish: Torio CAS#: 7440-29-1 #### What is thorium? Thorium is a naturally occurring radioactive substance found in small amount in rocks, soil, and water. There are four naturally occurring forms of thorium. As thorium breaks down, it releases small amounts of radiation. Thorium can be used to make ceramics, gas lantern mantles, and metals used in the aerospace industry and in nuclear reactions. Thorium can also be used as a fuel for generating nuclear energy. [...] Thorium is a naturally occurring element found at very low levels in the air, food and drinking water. It is not easily taken up by your body. It is unlikely that health effects will occur in the general population. [...] From 1928–1955, a solution of thorium was given to people for special x-ray tests. In patients given high amounts of thorium, an increase in the number of cancers of the liver, gall bladder, and blood was found. The U.S. Department of Health and Human Services (DHHS) has classified thorium as resonably antipated to be a human carcinogen (causing cancer in people). The U.S. Environmental Protection Agency (EPA) has not determined whether thorium can cause cancer in people.

• Instance Of

  Q4167410

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. All known thorium isotopes are unstable. The most stable isotope, 232Th, has a half-life of 14.05 billion years, or about the age of the universe; it decays very slowly via alpha decay, starting a decay chain named the thorium series that ends at stable 208Pb. On Earth, thorium and uranium are the only significantly radioactive elements that still occur naturally in large quantities as primordial elements. 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 Jöns Jacob Berzelius, who named it after Thor, the Norse god of thunder. Its first applications were developed in the late 19th century. Thorium's radioactivity was widely acknowledged during the first decades of the 20th century. In the second half of the century, thorium was replaced in many uses due to concerns about its radioactivity. Thorium is still being used as an alloying element in TIG welding electrodes but is slowly being replaced in the field with different compositions. It was also material in high-end optics and scientific instrumentation, used in some broadcast vacuum tubes, and as the light source in gas mantles, but these uses have become marginal. It has been suggested as a replacement for uranium as nuclear fuel in nuclear reactors, and several thorium reactors have been built. Thorium is also 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. Other uses for thorium include heat-resistant ceramics, aircraft engines, and in light bulbs. Ocean science has utilised 231Pa/230Th isotope ratios to understand the ancient ocean.