Thorium

Thorium,  ₉₀Th

General properties
Appearance	sillery, eften wi black tarnish
Staundart atomic wecht (Ar, staundart)	7002232037700000000♠232.0377(4)
Thorium in the periodic cairt
Hydrogen Helium Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Airn Cobalt Nickel Capper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Siller (element) Cadmium Indium Tin Antimony Tellurium Iodine Xenon Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gowd Mercur (element) Thallium Leid (element) Bismuth Polonium Astatine Radon Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Ununtrium Flerovium Ununpentium Livermorium Ununseptium Ununoctium Ce ↑ Th ↓ (Uqb) actinium ← thorium → protactinium
Atomic nummer (Z)	90
Group	group n/a
Period	period 7
Element category	actinide
Block	f-block
Electron confeeguration	[Rn] 6d2 7s2
Electrons per shell	2, 8, 18, 32, 18, 10, 2
Pheesical properties
Phase (at STP)	solit
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
Spectral lines
Miscellanea
Creestal structur	​face-centred cubic (fcc)
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
Young's modulus	79 GPa
Shear modulus	31 GPa
Bouk modulus	54 GPa
Poisson ratio	0.27
Mohs haurdness	3.0
Vickers haurdness	350 MPa
Brinell haurdness	400 MPa
CAS Nummer	7440-29-1
History
Diskivery	Jöns Jakob Berzelius (1829)
Main isotopes o thorium
Iso­tope Abun­dance Hauf-life (t1/2) Decay mode Pro­duct 228Th trace 1.9116 y α 224Ra 229Th trace 7340 y α 225Ra 230Th trace 75380 y α 226Ra 231Th trace 25.5 h β− 231Pa 232Th 100% 1.405×1010 y α 228Ra 234Th trace 24.1 d β− 234Pa

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.