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Thorium,  90Th
Thorium sample 0.1g.jpg
General properties
Name, seembol thorium, Th
Appearance sillery, eften wi black tarnish
Pronunciation /ˈθɔəriəm/
Thorium in the periodic cairt
Hydrogen (diatomic nonmetal)
Helium (noble gas)
Lithium (alkali metal)
Beryllium (alkaline yird metal)
Boron (metalloid)
Carbon (polyatomic nonmetal)
Nitrogen (diatomic nonmetal)
Oxygen (diatomic nonmetal)
Fluorine (diatomic nonmetal)
Neon (noble gas)
Sodium (alkali metal)
Magnesium (alkaline yird metal)
Aluminium (post-transeetion metal)
Silicon (metalloid)
Phosphorus (polyatomic nonmetal)
Sulfur (polyatomic nonmetal)
Chlorine (diatomic nonmetal)
Argon (noble gas)
Potassium (alkali metal)
Calcium (alkaline yird metal)
Scandium (transeetion metal)
Titanium (transeetion metal)
Vanadium (transeetion metal)
Chromium (transeetion metal)
Manganese (transeetion metal)
Airn (transeetion metal)
Cobalt (transeetion metal)
Nickel (transeetion metal)
Capper (transeetion metal)
Zinc (transeetion metal)
Gallium (post-transeetion metal)
Germanium (metalloid)
Arsenic (metalloid)
Selenium (polyatomic nonmetal)
Bromine (diatomic nonmetal)
Krypton (noble gas)
Rubidium (alkali metal)
Strontium (alkaline yird metal)
Yttrium (transeetion metal)
Zirconium (transeetion metal)
Niobium (transeetion metal)
Molybdenum (transeetion metal)
Technetium (transeetion metal)
Ruthenium (transeetion metal)
Rhodium (transeetion metal)
Palladium (transeetion metal)
Siller (transeetion metal)
Cadmium (transeetion metal)
Indium (post-transeetion metal)
Tin (post-transeetion metal)
Antimony (metalloid)
Tellurium (metalloid)
Iodine (diatomic nonmetal)
Xenon (noble gas)
Caesium (alkali metal)
Barium (alkaline yird metal)
Lanthanum (lanthanide)
Cerium (lanthanide)
Praseodymium (lanthanide)
Neodymium (lanthanide)
Promethium (lanthanide)
Samarium (lanthanide)
Europium (lanthanide)
Gadolinium (lanthanide)
Terbium (lanthanide)
Dysprosium (lanthanide)
Holmium (lanthanide)
Erbium (lanthanide)
Thulium (lanthanide)
Ytterbium (lanthanide)
Lutetium (lanthanide)
Hafnium (transeetion metal)
Tantalum (transeetion metal)
Tungsten (transeetion metal)
Rhenium (transeetion metal)
Osmium (transeetion metal)
Iridium (transeetion metal)
Platinum (transeetion metal)
Gold (transeetion metal)
Mercur (transeetion metal)
Thallium (post-transeetion metal)
Leid (post-transeetion metal)
Bismuth (post-transeetion metal)
Polonium (post-transeetion metal)
Astatine (metalloid)
Radon (noble gas)
Francium (alkali metal)
Radium (alkaline yird metal)
Actinium (actinide)
Thorium (actinide)
Protactinium (actinide)
Uranium (actinide)
Neptunium (actinide)
Plutonium (actinide)
Americium (actinide)
Curium (actinide)
Berkelium (actinide)
Californium (actinide)
Einsteinium (actinide)
Fermium (actinide)
Mendelevium (actinide)
Nobelium (actinide)
Lawrencium (actinide)
Rutherfordium (transeetion metal)
Dubnium (transeetion metal)
Seaborgium (transeetion metal)
Bohrium (transeetion metal)
Hassium (transeetion metal)
Meitnerium (unkent chemical properties)
Darmstadtium (unkent chemical properties)
Roentgenium (unkent chemical properties)
Copernicium (transeetion metal)
Ununtrium (unkent chemical properties)
Flerovium (post-transeetion metal)
Ununpentium (unkent chemical properties)
Livermorium (unkent chemical properties)
Ununseptium (unkent chemical properties)
Ununoctium (unkent chemical properties)


Atomic nummer (Z) 90
Group, block group n/a, f-block
Period period 7
Element category   actinide
Staundart atomic wicht (±) (Ar) 232.0377(4)
Electron configuration [Rn] 6d2 7s2
per shell
2, 8, 18, 32, 18, 10, 2
Pheesical properties
Phase solid
Meltin pynt 2115 K ​(1842 °C, ​3348 °F)
Bylin pynt 5061 K ​(4788 °C, ​8650 °F)
Density near r.t. 11.7 g/cm3
Heat o fusion 13.81 kJ/mol
Heat o vapourisation 514 kJ/mol
Molar heat capacity 26.230 J/(mol·K)
vapour pressur
P (Pa) 1 10 100 1 k 10 k 100 k
at T (K) 2633 2907 3248 3683 4259 5055
Atomic properties
Oxidation states

4, 3, 2, 1

(weakly basic oxide)
Electronegativity Pauling scale: 1.3
Atomic radius empirical: 179 pm
Covalent radius 206±6 pm
Crystal structur face-centered cubic (fcc)
Face-centered cubic crystal structur for thorium
Speed o soond thin rod 2490 m/s (at 20 °C)
Thermal expansion 11.0 µm/(m·K) (at 25 °C)
Thermal conductivity 54.0 W/(m·K)
Electrical resistivity 147 n Ω·m (at 0 °C)
Magnetic orderin paramagnetic[1]
Young's modulus 79 GPa
Shear modulus 31 GPa
Bulk modulus 54 GPa
Poisson ratio 0.27
Mohs haurdness 3.0
Vickers haurdness 350 MPa
Brinell haurdness 400 MPa
CAS Nummer 7440-29-1
Discovery Jöns Jakob Berzelius (1829)
Maist stable isotopes o thorium
iso NA hauf-life DM DE (MeV) DP
228Th trace 1.9116 y α 5.520 224Ra
229Th trace 7340 y α 5.168 225Ra
230Th trace 75380 y α 4.770 226Ra
231Th trace 25.5 h β 0.39 231Pa
232Th 100% 1.405×1010 y α 4.083 228Ra
234Th trace 24.1 d β 0.27 234Pa
· references

Thorium is a naiturally occurrin radioactive chemical element wi the seembol Th an atomic nummer 90. It wis discovered in 1828 bi the Norwegian mineralogist Morten Thrane Esmark an identified bi the Swadish chemist Jöns Jakob Berzelius an named efter Thor, the Norse god o thunner.

References[eedit | eedit soorce]

  1. Magnetic susceptibility of the elements and inorganic compounds, in Handbook of Chemistry and Physics 81st edition, CRC press.