90 actinium ← thorium → protactinium Ce ↑ Th ↓ (Uqn) Periodic Table - Extended Periodic Table
General
Name, Symbol, Number	thorium, Th, 90
Chemical series	Actinides
Group, Period, Block	n/a, 7, f
Appearance	silvery white
Standard atomic weight	232.0381(2)  g·mol−1
Electron configuration	[Rn] 6d2 7s2
Electrons per shell	2, 8, 18, 32, 18, 10, 2
Physical properties
Phase	solid
Density (near r.t.)	11. Actinium (ækˈtɪniəm is a radioactive Chemical element with the symbol Ac and Atomic number 89 which was discovered in 1899, the earliest Protactinium (ˌproʊtækˈtɪniəm is a Chemical element with the symbol Pa and Atomic number 91 Cerium (ˈsɪəriəm is a Chemical element with the symbol Ce and Atomic number 58 This is a typical display of the periodic table of the elements and contains the symbol and Atomic number of each element Wikipedia talkFeatured lists for an explanation of this and other inclusion tags below -->This is a list of Chemical elements, sorted by name Wikipedia talkFeatured lists for an explanation of this and other inclusion tags below -->This is a list of chemical elements by symbol, including the A table of Chemical elements ordered by Atomic number and color coded according to type of element In Chemistry a group, also known as a family, is a vertical column in the Periodic table of the Chemical elements There are 18 groups in History of the actinoid series From the earlier known chemical properties of actinium (89 up to uranium (92 indicating a relation to the Transition metals it was generally In Chemistry a group, also known as a family, is a vertical column in the Periodic table of the Chemical elements There are 18 groups in In the Periodic table of the elements, a period is a horizontal row of the table A block of the Periodic table of elements is a set of adjacent groups The respective highest-energy electrons in each element in a block belong to the same Atomic Occurrence Scandium yttrium and the Lanthanides (except promethium tend to occur together in the Earth's crust and are relatively abundant compared with most D-block A period 7 element is one of the Chemical elements in the seventh row (or period) of the periodic table of the elements. The f-block of the Periodic table of the elements consists of those elements (sometimes referred to as the inner transition elements) for which in the The atomic mass (ma is the Mass of an atom most often expressed in unified atomic mass units The atomic mass may be considered to be the total mass To help compare different orders of magnitude, the following list describes various Mass levels between 10&minus36&thinsp kg and 1053&thinspkg In Atomic physics and Quantum chemistry, electron configuration is the arrangement of Electrons in an Atom, Molecule, or other Radon (ˈreɪdɒn is the Chemical element that has the symbol Rn and Atomic number 86 The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J An electron shell may be crudely thought of as an Orbit followed by Electrons around an Atom nucleus. In the Physical sciences a phase is a Set of states of a macroscopic physical system that have relatively uniform chemical composition and physical properties A solid' object is in the States of matter characterized by resistance to Deformation and changes of Volume. The density of a material is defined as its Mass per unit Volume: \rho = \frac{m}{V} Different materials usually have different Room temperature (also referred to as ambient temperature) is a common term to denote a certain Temperature within enclosed space at which humans are accustomed 7  g·cm−3
Melting point	2115 K (1842 °C, 3348 °F)
Boiling point	5061 K (4788 °C, 8650 °F)
Heat of fusion	13. The melting point of a solid is the temperature range at which it changes state from solid to Liquid. The kelvin (symbol K) is a unit increment of Temperature and is one of the seven SI base units The Kelvin scale is a thermodynamic The Celsius Temperature scale was previously known as the centigrade scale. Fahrenheit is a temperature scale named after Daniel Gabriel Fahrenheit (1686–1736 a German Physicist who proposed it in 1724 The boiling point of a liquid is the temperature at which the Vapor pressure of the liquid equals the environmental pressure surrounding the liquid The kelvin (symbol K) is a unit increment of Temperature and is one of the seven SI base units The Kelvin scale is a thermodynamic The Celsius Temperature scale was previously known as the centigrade scale. Fahrenheit is a temperature scale named after Daniel Gabriel Fahrenheit (1686–1736 a German Physicist who proposed it in 1724 The standard Enthalpy of fusion (symbol \Delta{}H_{fus} also known as the heat of fusion or specific melting heat, is the amount of 81  kJ·mol−1
Heat of vaporization	514  kJ·mol−1
Specific heat capacity	(25 °C) 26. The joule per mole (symbol J·mol-1 is an SI derived unit of energy per amount of material The enthalpy of vaporization, (symbol \Delta{}_{v}H also known as the heat of vaporization or heat of evaporation, is the Energy required The joule per mole (symbol J·mol-1 is an SI derived unit of energy per amount of material Specific heat capacity, also known simply as specific heat, is the measure of the heat energy required to increase the Temperature of a unit quantity 230  J·mol−1·K−1
Vapor pressure P(Pa) 1 10 100 1 k 10 k 100 k at T(K) 2633 2907 3248 3683 4259 5055
Atomic properties
Crystal structure	cubic face centered
Oxidation states	4 (weakly basic oxide)
Electronegativity	1. Vapor pressure (also known as equilibrium vapor pressure or saturation vapor pressure) is the Pressure of a Vapor in equilibrium In Mineralogy and Crystallography, a crystal structure is a unique arrangement of Atoms in a Crystal. In Chemistry, the oxidation state is an indicator of the degree of Oxidation of an Atom in a Chemical compound. In Chemistry, a base is most commonly thought of as an aqueous substance that can accept Protons This refers to the Brønsted-Lowry theory of acids and " Electronegativity " is the opposite of " Electropositivity," which describes an element's ability to donate electrons 3 (Pauling scale)
Ionization energies (more)	1st:  587  kJ·mol−1
	2nd:  1110  kJ·mol−1
	3rd:  1930  kJ·mol−1
Atomic radius	180  pm
Miscellaneous
Magnetic ordering	no data
Electrical resistivity	(0 °C) 147 nΩ·m
Thermal conductivity	(300 K) 54. The ionization potential, ionization energy or EI of an Atom or Molecule is the Energy required to remove an Electron These tables list the Ionization energy in kJ/mol necessary to remove one mole of Electrons from one mole of neutral gaseous Atoms (first energy respectively The joule per mole (symbol J·mol-1 is an SI derived unit of energy per amount of material Atomic radius, and more generally the size of an atom, is not a precisely defined Physical quantity, nor is it constant in all circumstances A picometre ( American spelling: picometer, symbol pm) is a unit of Length in the Metric system, equal to one trillionth In Physics, magnetism is one of the Phenomena by which Materials exert attractive or repulsive Forces on other Materials. Electrical resistivity (also known as specific electrical resistance) is a measure of how strongly a material opposes the flow of Electric current. In Physics, thermal conductivity, k is the property of a material that indicates its ability to conduct Heat. 0  W·m−1·K−1
Thermal expansion	(25 °C) 11. When the Temperature of a substance changes the energy that is stored in the Intermolecular bonds between atoms changes 0  µm·m−1·K−1
Speed of sound (thin rod)	(20 °C) 2490 m/s
Young's modulus	79  GPa
Shear modulus	31  GPa
Bulk modulus	54  GPa
Poisson ratio	0. Sound is a vibration that travels through an elastic medium as a Wave. In Solid mechanics, Young's modulus (E is a measure of the Stiffness of an isotropic elastic material In Materials science, shear modulus or modulus of rigidity, denoted by G, or sometimes S or μ, is defined as the ratio of Shear Poisson's ratio ( ν) named after Simeon Poisson, is the ratio of the relative contraction strain, or transverse strain (normal to 27
Mohs hardness	3. The Mohs scale of mineral hardness characterizes the scratch resistance of various Minerals through the ability of a harder material to scratch a softer material 0
Vickers hardness	350  MPa
Brinell hardness	400  MPa
CAS registry number	7440-29-1
Selected isotopes
Main article: Isotopes of thorium iso NA half-life DM DE (MeV) DP 228Th syn 1. The Vickers hardness test was developed in 1924 by Smith and Sandland as an alternative method to measure the Hardness of materials The Brinell scale characterizes the indentation Hardness of materials through the scale of penetration of an indenter loaded on a material test-piece CAS registry numbers are unique numerical identifiers for Chemical compounds Polymers biological sequences mixtures and Alloys They are also referred to Although Thorium ( Th) has multiple Isotopes, none of these isotopes are stable however one isotope is relatively stable ( 232Th Isotopes (Greek isos = "equal" tópos = "site place" are any of the different types of atoms ( Nuclides In Chemistry, natural abundance (NA refers to the abundance Isotopes of a Chemical element as naturally found on a planet Half-Life (computer-game page here It's already listed in the disambiguation page Radioactive decay is the process in which an unstable Atomic nucleus loses energy by emitting ionizing particles and Radiation. The decay energy is the Energy released by a Nuclear decay. The energy difference of the Reactants is often written as Q: where Q In Nuclear physics, a decay product, also known as a daughter product, daughter isotope or daughter nuclide, is a Nuclide A synthetic radioisotope is a Radionuclide that is not found in nature no natural process or mechanism exists which produces it or it is so unstable that it decays away in 9116 years α 5. A year (from Old English gēr) is the time between two recurrences of an event related to the Orbit of the Earth around the Sun Alpha decay is a type of radioactive decay in which an Atomic nucleus emits an Alpha particle (two protons and two neutrons bound together into a particle 520 224Ra 229Th syn 7340 years α 5. Radium (ˈreɪdiəm is a radioactive Chemical element which has the symbol Ra and Atomic number 88 A synthetic radioisotope is a Radionuclide that is not found in nature no natural process or mechanism exists which produces it or it is so unstable that it decays away in A year (from Old English gēr) is the time between two recurrences of an event related to the Orbit of the Earth around the Sun Alpha decay is a type of radioactive decay in which an Atomic nucleus emits an Alpha particle (two protons and two neutrons bound together into a particle 168 225Ra 230Th syn 75380 years α 4. Radium (ˈreɪdiəm is a radioactive Chemical element which has the symbol Ra and Atomic number 88 A synthetic radioisotope is a Radionuclide that is not found in nature no natural process or mechanism exists which produces it or it is so unstable that it decays away in A year (from Old English gēr) is the time between two recurrences of an event related to the Orbit of the Earth around the Sun Alpha decay is a type of radioactive decay in which an Atomic nucleus emits an Alpha particle (two protons and two neutrons bound together into a particle 770 226Ra 231Th trace 25. Radium (ˈreɪdiəm is a radioactive Chemical element which has the symbol Ra and Atomic number 88 A trace radioisotope is a Radioisotope that occurs naturally in trace amounts (i 5 hours β 0. The hour (symbol h) is a unit of Time. It is not an SI unit but is accepted for use with the SI In Nuclear physics, beta decay is a type of Radioactive decay in which a Beta particle (an Electron or a Positron) is emitted 39 231Pa 232Th 100% 1. Protactinium (ˌproʊtækˈtɪniəm is a Chemical element with the symbol Pa and Atomic number 91 405×1010 years α 4. A year (from Old English gēr) is the time between two recurrences of an event related to the Orbit of the Earth around the Sun Alpha decay is a type of radioactive decay in which an Atomic nucleus emits an Alpha particle (two protons and two neutrons bound together into a particle 083 228Ra 234Th trace 24. Radium (ˈreɪdiəm is a radioactive Chemical element which has the symbol Ra and Atomic number 88 A trace radioisotope is a Radioisotope that occurs naturally in trace amounts (i 1 days β 0. A day (symbol d is a unit of Time equivalent to 24 Hours and the duration of a single Rotation of planet Earth with respect to the In Nuclear physics, beta decay is a type of Radioactive decay in which a Beta particle (an Electron or a Positron) is emitted 27 234Pa
References

Thorium (pronounced /ˈθɔriəm/) is a chemical element with the symbol Th and atomic number 90. Protactinium (ˌproʊtækˈtɪniəm is a Chemical element with the symbol Pa and Atomic number 91 Recommended values for many properties of the elements together with various references are collected on these data pages A chemical element is a type of Atom that is distinguished by its Atomic number; that is by the number of Protons in its nucleus. See also List of elements by atomic number In Chemistry and Physics, the atomic number (also known as the proton As a naturally occurring, slightly radioactive metal, it has been considered as an alternative nuclear fuel to uranium. Uranium (jʊˈreɪniəm is a silvery-gray Metallic Chemical element in the

Notable characteristics

When pure, thorium is a silvery white metal that retains its luster for several months. However, when it is exposed to oxygen, thorium slowly tarnishes in air, becoming grey and eventually black. Thorium dioxide (ThO₂), also called thoria, has the highest melting point of any oxide (3300°C). Thorium dioxide (ThO2 also called thorium(IV oxide (IUPAC is a white crystalline powder ^[1] When heated in air, thorium metal turnings ignite and burn brilliantly with a white light. Swarf (or turnings or chips are shavings and chippings of metal—the debris or waste resulting from Metalworking operations

Thorium has the largest liquid range of any element: 2946 K between the melting point and boiling point.

See Actinides in the environment for details of the environmental aspects of thorium. Actinides in the environment refer to the sources environmental behaviour and effects of Actinides in the environment.

Applications

Applications of thorium:

• As an alloying element in magnesium, used in aircraft engines, imparting high strength and creep resistance at elevated temperatures. An alloy is a Solid solution or Homogeneous mixture of two or more elements, at least one of which is a Metal, which itself has Magnesium (mægˈniːziəm is a Chemical element with the symbol Mg, Atomic number 12 Atomic weight 24 In Materials science, the strength of a material refers to the material's ability to resist an applied force Creep is the tendency of a solid material to slowly move or deform permanently under the influence of stresses It occurs as a result of long term exposure to levels of
• Thorium is used to coat tungsten wire used in electronic equipment, improving the electron emission of heated cathodes. Tungsten (ˈtʌŋstən also known as wolfram (/ˈwʊlfrəm/ is a Chemical element that has the symbol W and Atomic number 74 The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J Thermionic emission is the flow of Charge carriers from a surface or over some other kind of Electrical potential barrier caused by thermal vibrational energy A cathode is an Electrode through which (positive Electric current flows out of a polarized electrical device
• Uranium-thorium age dating has been used to date hominid fossils. Uranium-thorium dating, also called thorium-230 dating, uranium-series disequilibrium dating or uranium-series dating, is a Radiometric dating FOSSIL is a standard protocol for allowing serial communication for Telecommunications programs under the DOS Operating system.
• As a fertile material for producing nuclear fuel. Fertile material is a term used to describe Nuclides which generally themselves do not undergo induced fission (fissionable by thermal Neutrons) but from Nuclear fuel is any material that can be consumed to derive Nuclear energy, by analogy to chemical Fuel that is burned to derive energy In particular, the proposed energy amplifier reactor design would employ thorium. In Nuclear physics, an energy amplifier is a novel type of Nuclear power reactor a Subcritical reactor, in which an energetic particle Since thorium is more abundant than uranium, some nuclear reactor designs incorporate thorium in their fuel cycle. This article is a subarticle of Nuclear power. A nuclear reactor is a device in which Nuclear chain reactions are initiated controlled The nuclear fuel cycle, also called nuclear fuel chain, is the progression of Nuclear fuel through a series of differing stages
• Thorium is a very effective radiation shield, although it has not been used for this purpose as much as lead or depleted uranium. Radiation protection, sometimes known as radiological protection, is the science of protecting people and the environment from the harmful effects of Ionizing radiation Characteristics Lead has a dull luster and is a dense, Ductile, very soft highly Depleted uranium (DU is Uranium primarily composed of the Isotope Uranium-238 (U-238
• Thorium may be used in nuclear reactors instead of uranium as fuel. This article is a subarticle of Nuclear power. A nuclear reactor is a device in which Nuclear chain reactions are initiated controlled This produces less transuranic waste. Transuranic waste is defined as Waste containing more than 100 nanocuries of alpha-emitting transuranic isotopes per gram of waste with half-lives greater than 20 years except

Applications of thorium dioxide (ThO₂):

• Mantles in portable gas lights. Thorium dioxide (ThO2 also called thorium(IV oxide (IUPAC is a white crystalline powder For other uses of mantle see Mantle An incandescent gas mantle, gas mantle, or Welsbach mantle is a device for generating These mantles glow with a dazzling light (unrelated to radioactivity) when heated in a gas flame.
• Used in gas tungsten arc welding electrodes. Gas tungsten arc welding ( GTAW) also known as tungsten inert gas (TIG welding, is an Arc welding process that uses a nonconsumable Tungsten
• Used to control the grain size of tungsten used for electric lamps. Tungsten (ˈtʌŋstən also known as wolfram (/ˈwʊlfrəm/ is a Chemical element that has the symbol W and Atomic number 74
• Used in heat-resistant ceramics like high-temperature laboratory crucibles. In Metallurgy, refraction is a property of Metals that indicates their ability to withstand Heat. The word ceramic is derived from the Greek word κεραμικός ( keramikos) A crucible is a cup-shaped piece of laboratory object Laboratory equipment used to contain Chemical compounds when heating them to very high Temperatures
• Added to glass, it helps create glasses of a high refractive index and with low dispersion. Glass in the common sense refers to a Hard, Brittle, transparent Solid, such as that used for Windows many The refractive index (or index of Refraction) of a medium is a measure for how much the speed of light (or other waves such as sound waves is reduced inside the medium In Optics, dispersion is the phenomenon in which the Phase velocity of a wave depends on its frequency Consequently, they find application in high-quality lenses for cameras and scientific instruments. A lens is an optical device with perfect or approximate Axial symmetry which transmits and refracts Light, converging or diverging
• Has been used as a catalyst:
  • In the conversion of ammonia to nitric acid. Catalysis is the process in which the rate of a Chemical reaction is increased by means of a Chemical substance known as a catalyst Ammonia is a compound with the formula N[[hydrogen H3]] It is normally encountered as a Gas with a characteristic pungent Odor Nitric acid ( H[[nitrate NO3]] also known as Aqua fortis and spirit of nitre, is a highly corrosive and
  • In petroleum cracking. Petroleum ( L petroleum, from Greek πετρέλαιον, lit In Petroleum geology and Chemistry, cracking is the process whereby complex organic Molecules such as Kerogens or heavy Hydrocarbons
  • In producing sulfuric acid. Sulfuric (or sulphuric acid, H 2 S[[oxygen O]]4 is a strong Mineral acid.
• Thorium dioxide is the active ingredient of Thorotrast, which was used as part of X-ray diagnostics. Thorotrast is a suspension containing particles of the radioactive compound Thorium dioxide, ThO2 used as a Contrast medium in X-radiation (composed of X-rays) is a form of Electromagnetic radiation. This use has been abandoned due to the carcinogenic nature of Thorotrast. The term carcinogen refers to any substance Radionuclide or radiation that is an agent directly involved in the promotion of Cancer or in the fatation of its propagation

History

M. T. Esmark found a black mineral on Løvøy Island, Norway and gave a sample to Professor Jens Esmark, a noted mineralogist who was not able to identify it so he sent a sample to the Swedish chemist Jöns Jakob Berzelius for examination in 1828. Norway ( Norwegian: Norge ( Bokmål) or Noreg ( Nynorsk) officially the Kingdom of Norway, is a Constitutional Jens Esmark (1763–1839 was an expert mountain climber and professor of Mineralogy who contributed to many of the initial discoveries and conceptual analyses of Glaciers Mineralogy is an Earth Science focused around the Chemistry, Crystal structure, and physical (including optical) properties of Minerals Friherre Jöns Jacob Berzelius (20 August 1779 &ndash 7 August 1848 was a Swedish chemist ^[2] Berzelius analysed it and named it after Thor, the Norse god of thunder. Thor ( Old Norse: Þórr) is the red-haired and bearded God of Thunder in Germanic paganism and its subset Norse paganism Norse mythology comprises the indigenous pre-Christian religion, beliefs and Legends of the Scandinavian peoples including those who settled on Iceland The metal had virtually no uses until the invention of the gas mantle in 1885. For other uses of mantle see Mantle An incandescent gas mantle, gas mantle, or Welsbach mantle is a device for generating

Between 1900 and 1903 Ernest Rutherford and Frederick Soddy showed how thorium decayed at a fixed rate over time into a series of other elements. Ernest Rutherford 1st Baron Rutherford of Nelson, OM, PC, FRS (30 August 1871 – 19 October 1937 was a New Zealand Physicist Frederick Soddy ( 2 September 1877 &ndash 22 September 1956) was an English radiochemist. This observation led to the identification of half life as one of the outcomes of the alpha particle experiments that led to their disintegration theory of radioactivity. Half-Life (computer-game page here It's already listed in the disambiguation page Alpha particles (named after and denoted by the first letter in the Greek alphabet, α consist of two Protons and two Neutrons bound together into a Radioactive decay is the process in which an unstable Atomic nucleus loses energy by emitting ionizing particles and Radiation. ^[3]

The crystal bar process (or Iodide process) was discovered by Anton Eduard van Arkel and Jan Hendrik de Boer in 1925 to produce high-purity metallic thorium. The crystal bar process (or iodide process) was discovered by Anton Eduard van Arkel and Jan Hendrik de Boer in 1925 Anton Eduard van Arkel, ( 's-Gravenzande Netherlands, November 19, 1893 &ndash Leiden, March 14 1976) was a ^[4]

The name ionium was given early in the study of radioactive elements to the ²³⁰Th isotope produced in the decay chain of ²³⁸U before it was realized that ionium and thorium were chemically identical. Isotopes (Greek isos = "equal" tópos = "site place" are any of the different types of atoms ( Nuclides In Nuclear science, the decay chain refers to the Radioactive decay of different discrete radioactive decay products as a chained series of transformations Uranium-238 (U-238 is the most common isotope of Uranium found in nature The symbol Io was used for this supposed element.

Occurrence

Monazite, a rare-earth-and-thorium-phosphate mineral, is the primary source of the world's thorium

Thorium is found in small amounts in most rocks and soils, where it is about three times more abundant than uranium, and is about as common as lead. Soil, often typeset as SOiL, is a four piece rock band from Chicago Illinois United States founded by Shaun Glass Tom Schofield Tim King and Adam Zadel Uranium (jʊˈreɪniəm is a silvery-gray Metallic Chemical element in the Characteristics Lead has a dull luster and is a dense, Ductile, very soft highly Soil commonly contains an average of around 12 parts per million (ppm) of thorium. Thorium occurs in several minerals, the most common being the rare-earth thorium-phosphate mineral monazite, which contains up to about 12% thorium oxide. A mineral is a naturally occurring substance formed through geological processes that has a characteristic chemical composition a highly ordered atomic structure and specific In Geology, the Mineral monazite is a reddish-brown Phosphate -containing rare earth metals and an important source of Thorium There are substantial deposits in several countries. ²³²Th decays very slowly (its half-life is about three times the age of the earth) but other thorium isotopes occur in the thorium and uranium decay chains. Half-Life (computer-game page here It's already listed in the disambiguation page Isotopes (Greek isos = "equal" tópos = "site place" are any of the different types of atoms ( Nuclides Uranium (jʊˈreɪniəm is a silvery-gray Metallic Chemical element in the Most of these are short-lived and hence much more radioactive than ²³²Th, though on a mass basis they are negligible. India is believed to have 25% of the world's thorium reserves. ^[5]

See also thorium minerals.

Distribution

Present knowledge of the distribution of thorium resources is poor because of the relatively low-key exploration efforts arising out of insignificant demand. ^[6] Under the prevailing estimate, Australia and India have particularly large reserves of thorium. For a topic outline on this subject see List of basic Australia topics. India, officially the Republic of India (भारत गणराज्य inc-Latn Bhārat Gaṇarājya; see also other Indian languages) is a country

• The prevailing estimate of the economically available thorium reserves comes from the US Geological Survey, Mineral Commodity Summaries (1997-2006):^[7][8]

• Another estimate of Reasonably Assured Reserves (RAR) and Estimated Additional Reserves (EAR) of thorium comes from OECD/NEA, Nuclear Energy, "Trends in Nuclear Fuel Cycle", Paris, France (2001). ^[9]

The two sources vary wildly for countries such as Brazil, Turkey, and Australia.

Thorium as a nuclear fuel

Thorium metal foil (approximately 0. 5 mm thick) sealed in a glass ampoule under an argon atmosphere to prevent oxidation

Thorium, as well as uranium and plutonium, can be used as fuel in a nuclear reactor. Uranium (jʊˈreɪniəm is a silvery-gray Metallic Chemical element in the This article is a subarticle of Nuclear power. A nuclear reactor is a device in which Nuclear chain reactions are initiated controlled Although not fissile itself, ²³²Th will absorb slow neutrons to produce (²³³U), which is fissile. In Nuclear engineering, a fissile material is one that is capable of sustaining a Chain reaction of Nuclear fission. The neutron temperature, also called the neutron energy, indicates a free neutron's Kinetic energy, usually given in Electron volts The term Uranium-233 is a Fissile artificial isotope of Uranium, which has been used in a few Nuclear reactors and has been proposed for much wider use as a Hence, like ²³⁸U, it is fertile. Uranium-238 (U-238 is the most common isotope of Uranium found in nature Fertile material is a term used to describe Nuclides which generally themselves do not undergo induced fission (fissionable by thermal Neutrons) but from In one significant respect ²³³U is better than the other two fissile isotopes used for nuclear fuel, ²³⁵U and plutonium-239 (²³⁹Pu), because of its higher neutron yield per neutron absorbed. Uranium-235 is an isotope of uranium that differs from the element's other common isotope Uranium-238, by its ability to cause a rapidly expanding fission Plutonium-239 is an Isotope of Plutonium. Plutonium-239 is the primary Fissile isotope used for the production of Nuclear weapons although Given a start with some other fissile material (²³⁵U or ²³⁹Pu), a breeding cycle similar to, but more efficient than that currently possible with the ²³⁸U-to-²³⁹Pu cycle (in slow-neutron reactors), can be set up. A breeder reactor is a Nuclear reactor that generates new Fissile or fissionable material at a greater rate than it consumes such material A thermal reactor has moderating materials to reduce the speed of Neutrons to low velocity Thermal neutrons so that Uranium-235 will be more likely The ²³²Th absorbs a neutron to become ²³³Th which normally emits an electron and an anti-neutrino () by β⁻ decay to become protactinium-233 (²³³Pa) and then emits another electron and anti-neutrino by a second β⁻ decay to become ²³³U:

The irradiated fuel can then be unloaded from the reactor, the ²³³U separated from the thorium (a relatively simple process since it involves chemical instead of isotopic separation), and fed back into another reactor as part of a closed nuclear fuel cycle. The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J In Physics, antineutrinos, the Antiparticles of Neutrinos are neutral particles produced in nuclear Beta decay. In Nuclear physics, beta decay is a type of Radioactive decay in which a Beta particle (an Electron or a Positron) is emitted Protactinium (ˌproʊtækˈtɪniəm is a Chemical element with the symbol Pa and Atomic number 91 Isotope separation is the process of concentrating specific Isotopes of a Chemical element by removing other isotopes for example separating Natural uranium The nuclear fuel cycle, also called nuclear fuel chain, is the progression of Nuclear fuel through a series of differing stages

Problems include the high cost of fuel fabrication due partly to the high radioactivity of ²³³U which is a result of its contamination with traces of the short-lived ²³²U; the similar problems in recycling thorium due to highly radioactive ²²⁸Th; some weapons proliferation risk of ²³³U; and the technical problems (not yet satisfactorily solved) in reprocessing. Much development work is still required before the thorium fuel cycle can be commercialised, and the effort required seems unlikely while (or where) abundant uranium is available.

Nevertheless, the thorium fuel cycle, with its potential for breeding fuel without fast neutron reactors, holds considerable potential long-term benefits. The nuclear fuel cycle, also called nuclear fuel chain, is the progression of Nuclear fuel through a series of differing stages A fast neutron reactor or simply a fast reactor is a category of Nuclear reactor in which the fission Chain reaction is sustained by Fast neutrons Thorium is significantly more abundant than uranium, and is a key factor in sustainable nuclear energy.

One of the earliest efforts to use a thorium fuel cycle took place at Oak Ridge National Laboratory in the 1960s. Oak Ridge National Laboratory ( ORNL) is a multiprogram science and technology National laboratory managed for the United States Department of Energy by An experimental reactor was built based on Molten Salt Reactor technology to study the feasibility of such an approach, using thorium-fluoride salt kept hot enough to be liquid, thus eliminating the need for fabricating fuel elements. A molten salt reactor (MSR is a type of Nuclear reactor where the primary coolant is a Molten salt. Fluoride is the reduced form of Fluorine. Both organic and Inorganic compounds containing the element fluorine are considered fluorides A salt, in Chemistry, is defined as the product formed from the neutralisation reaction of Acids and bases. This effort culminated in the Molten-Salt Reactor Experiment that used ²³²Th as the fertile material and ²³³U as the fissile fuel. The Molten-Salt Reactor Experiment (MSRE was an experimental Molten-salt reactor at the Oak Ridge National Laboratory (ORNL researching this technology through Due to a lack of funding, the MSR program was discontinued in 1976.

In 2007, Norway was debating whether or not to focus on thorium plants, due to the existence of large deposits of thorium ores in the country, particularly at Fensfeltet, near Ulefoss in Telemark county. Norway ( Norwegian: Norge ( Bokmål) or Noreg ( Nynorsk) officially the Kingdom of Norway, is a Constitutional is a county in Norway, bordering Vestfold, Buskerud, Hordaland, Rogaland and Aust-Agder.

The primary fuel of the HT³R Project near Odessa, Texas, USA will be ceramic-coated thorium beads. The High-Temperature Teaching and Test Reactor Energy Research Facility (nicknamed HT3R or "heater" is a proposed $457 million multi-purpose energy research facility that is Odessa is a city in Ector and Midland Counties in the US state of Texas. The United States of America —commonly referred to as the

Isotopes

Main article: isotopes of thorium

Naturally occurring thorium is composed of one isotope: ²³²Th. Although Thorium ( Th) has multiple Isotopes, none of these isotopes are stable however one isotope is relatively stable ( 232Th Isotopes (Greek isos = "equal" tópos = "site place" are any of the different types of atoms ( Nuclides Thorium-232 is the primary abundant Nuclide of Thorium. It is a slightly unstable Radionuclide that is found in the earth's crust Twenty-seven radioisotopes have been characterized, with the most abundant and/or stable being ²³²Th with a half-life of 14. A radionuclide is an Atom with an unstable nucleus, which is a nucleus characterized by excess energy which is available to be imparted either to a newly-created Half-Life (computer-game page here It's already listed in the disambiguation page 05 billion years, ²³⁰Th with a half-life of 75,380 years, ²²⁹Th with a half-life of 7340 years, and ²²⁸Th with a half-life of 1. 92 years. All of the remaining radioactive isotopes have half-lives that are less than thirty days and the majority of these have half-lives that are less than ten minutes. Radioactive decay is the process in which an unstable Atomic nucleus loses energy by emitting ionizing particles and Radiation. One isotope, ²²⁹Th, has a nuclear isomer (or metastable state) with a remarkably low excitation energy of 3. A nuclear isomer is a Metastable state of an Atomic nucleus caused by the excitation of one or more of its Nucleons A nuclear isomer occupies 5 eV. ^[10]

The known isotopes of thorium range in atomic weight from 210 u (²¹⁰Th) to 236 u (²³⁶Th). The atomic mass (ma is the Mass of an atom most often expressed in unified atomic mass units The atomic mass may be considered to be the total mass The unified atomic mass unit ( u) or Dalton ( Da) or sometimes universal mass unit, is an unit of Mass used to express ^[11]

Precautions

Powdered thorium metal is often pyrophoric and should be handled carefully. A pyrophoric substance will ignite spontaneously that is its Autoignition temperature is below Room temperature.

Natural thorium decays very slowly compared to many other radioactive materials, and the alpha radiation emitted cannot penetrate human skin. Alpha decay is a type of radioactive decay in which an Atomic nucleus emits an Alpha particle (two protons and two neutrons bound together into a particle Owning and handling small amounts of thorium, such as a gas mantle, is considered safe if care is taken not to ingest the thorium -- lungs and other internal organs can be penetrated by alpha radiation. For other uses of mantle see Mantle An incandescent gas mantle, gas mantle, or Welsbach mantle is a device for generating Exposure to aerosolized thorium can lead to increased risk of cancers of the lung, pancreas and blood. Cancer (medical term Malignant Neoplasm) is a class of Diseases in which a group of cells display uncontrolled lung is the essential Respiration organ in air-breathing Animals including most Tetrapods a few Fish and a few Snails The most primitive The pancreas is a Gland organ in the digestive and Endocrine system of Vertebrates. Blood is a specialized Bodily fluid that delivers necessary substances to the body's cells ��such as nutrients and oxygen—and transports Waste products Exposure to thorium internally leads to increased risk of liver diseases. The liver is a vital organ in the human body and is present in Vertebrates and some other animals This element has no known biological role. See also Thorotrast. Thorotrast is a suspension containing particles of the radioactive compound Thorium dioxide, ThO2 used as a Contrast medium in

Thorium Extraction

Thorium has been extracted chiefly from monazite through a multi-stage process. In the first stage, the monazite sand is dissolved in an anorganic acid such as sulfuric acid (H₂SO₄). In the second, the Thorium is extracted into an organic phase containing an amine. Next it is separated or "stripped" using an anion such as nitrate, chloride, hydroxide, or carbonate, returning the thorium to an aqueous phase. Finally, the thorium is precipitated and collected. ^[12]

See also

• David Hahn, who produced small quantities of fissionable material in his backyard. David Hahn (born October 30, 1976) is a man known for his attempt to build a Fast breeder Nuclear reactor in 1994 in his backyard shed in
• Periodic table
• Nuclear reactor
• Decay chain
• Sylvania Electric Products explosion

Footnotes

References

• Los Alamos National Laboratory — Thorium
• WebElements.com — Thorium
• The Uranium Information Centre provided some of the original material in this article. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 590 - Bahram Chobin is crowned as king Barham VI of Persia.
• European Nuclear Society — Natural Decay Chains

External links

• Thorium information page
• New Age Nuclear: article on thorium reactors | Cosmos Magazine
• ATSDR ToxFAQs — Thorium
• USGS data — Thorium
• The Endless Refrigerator/Freezer Deodorizer, a commercial product which claimed to destroy odours 'forever. ' Made with thorium-232.
• Is thorium the answer to our energy crisis?
• Thorium Energy Blog, discussion forum and document repository
• Another thorium information page