Thorium Elemental Symbol

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Thorium(Th) atomic and molecular weight, atomic number and elemental symbol Thorium is a Elemental ThoriumBlock F, Group 3, Period 7 element. The number of electrons in each of Thorium's shells is 2, 8, 18, 32, 18, 10, 2 and itThorium Bohr Models electron configuration is [Rn] 6d2 7s2. The thorium atom has a radius of and its Van der Waals radius is In its elemental form, CAS 7440-29-1, thorium has a silvery, sometimes black-tarnished, appearance. Thorium was first discovered by Jons Berzelius in 1829. It is found in small amounts in most rocks and soils. The name Thorium originates from the Scandinavian god Thor, the Norse god of war and thunder.

Thorium is a lanthanide (rare earth) material with potential nuclear power applications. It is presently used as a tungsten coating in electronic parts due to its high emission factor. In its fluoride and oxide forms, Thorium is used in advanced optic applications for its high refractive index. It is also used in several other high temperature glass applications, such as in the mantle of lamps and to produce crystal growth crucibles and ampules. High Purity (99.999%) Thorium (Th) Sputtering TargetThorium is available as metal and compounds with purities from 99% to 99.999% (ACS grade to ultra-high purity). High Purity (99.999%) Thorium Oxide (ThO2) PowderElemental or metallic forms include pellets, rod, wire and granules for evaporation source material purposes. Thorium nanoparticles and nanopowders provide ultra-high surface area which nanotechnology research and recent experiments demonstrate function to create new and unique properties and benefits. Oxides are available in powder and dense pellet form for such uses as optical coating and thin film applications. Oxides tend to be insoluble. Fluorides are another insoluble form for uses in which oxygen is undesirable such as metallurgy, chemical and physical vapor deposition and in some optical coatings. Thorium is also available in soluble forms including chlorides, nitrates and acetates. These compounds can be manufactured as solutions at specified stoichiometries.

Thorium is radioactive and can collect in bones which may cause bone cancer several years after exposure. Breathing in substantial amounts of thorium may be lethal. Safety data for Thorium and its compounds can vary widely depending on the form. For potential hazard information, toxicity, and road, sea and air transportation limitations, such as DOT Hazard Class, DOT Number, EU Number, NFPA Health rating and RTECS Class, please see the specific material or compound referenced in the Products tab below.

  • Properties
  • Products
  • Research
  • Isotopes
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Thorium Properties

Symbol: Th Melting Point: 2115 K, 1842 °C, 3348 °F
Atomic Number: 90 Boiling Point: 5061 K, 4788 °C, 8650 °F
Atomic Weight: 232 Density: 11.7 g·cm−3
Element Category: Actinide Liquid Density @ Melting Point: N/A
Group, Period, Block: n/a, 7, f Specific Heat: 0.13 kJ/kg K
    Heat of Vaporization 514 kJ·mol−1
CHEMICAL STRUCTURE Heat of Fusion 13.81 kJ·mol−1
Electrons: 90 Thermal Conductivity: 54.0 W·m−1·K−1
Protons: 90 Thermal Expansion: (25 °C) 11.0 µm·m−1·K−1
Neutrons: 142 Electrical Resistivity: (0 °C) 147 nΩ·m
Electron Configuration: [Rn]7s26d2 Electronegativity: 1.3 (Pauling scale)
Atomic Radius: 179 pm Tensile Strength: 144 MPa
Covalent Radius: 206±6 pm Molar Heat Capacity: 26.230 J·mol−1·K−1
Van der Waals radius: 237 pm Young's Modulus: 79 GPa
Oxidation States: 4, 3, 2, 1 (weakly basic oxide) Shear Modulus: 31 GPa
Phase: Solid Bulk Modulus: 54 GPa
Crystal Structure: face-centered cubic Poisson Ratio: 0.27
Magnetic Ordering: paramagnetic Mohs Hardness: 3.0
1st Ionization Energy: 587 kJ·mol−1 Vickers Hardness: 350 MPa
2nd Ionization Energy: 1110 kJ·mol−1 Brinell Hardness: 400 MPa
3rd Ionization Energy: 1930 kJ·mol−1 Speed of Sound: (20 °C) 2490 m·s−1
CAS Number: 7440-29-1 Abundance in typical human body, by weight: N/A
ChemSpider ID: 22399 Abundance in typical human body, by atom: N/A
PubChem CID: 23960 Abundance in universe, by weight: 0.4 ppb
MDL Number: N/A Abundance in universe, by atom: 0.002 ppb
EC Number: 231-139-7 Discovered By: Jöns Jakob Berzelius
Beilstein Number: N/A Discovery Date: 1829
SMILES Identifier: [Th]  
InChI Identifier: InChI=1S/Th Other Names:  

Thorium Products

Metal Forms  •  Compounds  •  Oxide Forms  •  Organometallic Compounds
Sputtering Targets  •  Nanomaterials  •  Semiconductor Materials

Recent Research & Development for Thorium

  • Thorium induced cytoproliferative effect in human liver cell HepG2: Role of insulin-like growth factor 1 receptor and downstream signaling. Ali M, Kumar A, Pandey BN. Chem Biol Interact. 2014.
  • Tetrapositive Plutonium, Neptunium, Uranium and Thorium Coordination Complexes: Chemistry Revealed by Electron Transfer and Collision Induced Dissociation. Gong Y, Tian G, Rao L, Gibson JK. J Phys Chem A. 2014.
  • Introduction of Bifunctional Groups into Mesoporous Silica for Enhancing Uptake of Thorium(IV) from Aqueous Solution. Yuan LY, Bai ZQ, Zhao R, Liu YL, Li ZJ, Chu SQ, Zheng LR, Zhang J, Zhao YL, Chai ZF, Shi WQ. ACS Appl Mater Interfaces. 2014.
  • (229)Thorium-doped calcium fluoride for nuclear laser spectroscopy. Dessovic P, Mohn P, Jackson RA, Winkler G, Schreitl M, Kazakov G, Schumm T. J Phys Condens Matter. 2014.
  • High-Temperature Phase Transitions, Spectroscopic Properties, and Dimensionality Reduction in Rubidium Thorium Molybdate Family. Xiao B, Gesing TM, Kegler P, Modolo G, Bosbach D, Schlenz H, Suleimanov EV, Alekseev EV. Inorg Chem. 2014.
  • Photochemical route to actinide-transition metal bonds: synthesis, characterization and reactivity of a series of thorium and uranium heterobimetallic complexes. Ward AL, Lukens WW, Lu CC, Arnold J. J Am Chem Soc. 2014.
  • The permanent electric dipole moment of thorium sulfide, ThS. Le A, Heaven MC, Steimle TC. J Chem Phys. 2014 Jan.
  • Thorotrast and in vivo thorium dioxide: Numerical simulation of 30 years of a radiation absorption by the tissues near a large compact source. Bianconi A. Phys Med. 2014 Feb
  • On the structure of thorium and americium adenosine triphosphate complexes. Mostapha S, Fontaine-Vive F, Berthon L, Boubals N, Zorz N, Solari PL, Charbonnel MC, Den Auwer C. Int J Radiat Biol. 2014.
  • The role of chemical interactions between thorium, cerium, and lanthanum in lymphocyte toxicity. Oliveira MS, Duarte IM, Paiva AV, Yunes SN, Almeida CE, Mattos RC, Sarcinelli PN. Arch Environ Occup Health. 2014.
  • Photochemical route to actinide-transition metal bonds: synthesis, characterization and reactivity of a series of thorium and uranium heterobimetallic complexes. Ward AL, Lukens WW, Lu CC, Arnold J. J Am Chem Soc. 2014.
  • Thorium and Uranium Carbide Cluster Cations in the Gas Phase: Similarities and Differences between Thorium and Uranium. Pereira CC, Maurice R, Lucena AF, Hu S, Gonçalves AP, Marçalo J, Gibson JK, Andrews L, Gagliardi L. Inorg Chem. 2013 create date:2013/09/21 | first author:Pereira CC
  • Thorium induced cytoproliferative effect in human liver cell HepG2: Role of insulin-like growth factor 1 receptor and downstream signaling. Ali M, Kumar A, Pandey BN. Chem Biol Interact. 2014.
  • Synthesis and Characterization of Thorium(IV) and Uranium(IV) Corrole Complexes. Ward AL, Buckley HL, Lukens WW, Arnold J. J Am Chem Soc. 2013 create date:2013/09/06 | first author:Ward AL
  • Systematic Investigation of Thorium(IV)- and Uranium(IV)-Ligand Bonding in Dithiophosphonate, Thioselenophosphinate, and Diselenophosphonate Complexes. Behrle AC, Barnes CL, Kaltsoyannis N, Walensky JR. Inorg Chem. 2013 | first author:Behrle AC
  • Comparison of the Reactivity of 2-Li-C(6) H(4) CH(2) NMe(2) with MCl(4) (M=Th, U): Isolation of a Thorium Aryl Complex or a Uranium Benzyne Complex. Seaman LA, Pedrick EA, Tsuchiya T, Wu G, Jakubikova E, Hayton TW. Angew Chem Int Ed Engl. 2013 | first author:Seaman LA
  • Thorium fluorides ThF, ThF2, ThF3, ThF4, ThF3(F2), and ThF5- characterized by infrared spectra in solid argon and electronic structure and vibrational frequency calculations. Andrews L, Thanthiriwatte KS, Wang X, Dixon DA. Inorg Chem. 2013 create date:2013/06/29 | first author:Andrews L
  • Ethyl thiosemicarbazide intercalated organophilic calcined hydrotalcite as a potential sorbent for the removal of uranium(VI) and thorium(IV) ions from aqueous solutions. Anirudhan TS, Jalajamony S. J Environ Sci (China). 2013 | first author:Anirudhan TS
  • Adsorption of lanthanides(III), uranium(VI) and thorium(IV) from nitric acid solutions by carbon inverse opals modified with tetraphenylmethylenediphospine dioxide. Turanov AN, Karandashev VK, Masalov VM, Zhokhov AA, Emelchenko GA. J Colloid Interface Sci. 2013 | first author:Turanov AN
  • Current commentary: thorium-based nuclear power. Rhodes CJ. Sci Prog. 2013 | first author:Rhodes CJ

Thorium Isotopes

Thorium (Th) has six naturally occuring isotopes. None of these are stable; however, 232Th is observationally stable with a half life of 14.05 billion years.

Nuclide Symbol Isotopic Mass Half-Life Nuclear Spin
232Th 232.0380553 1.405(6)×1010 0+