Template:Infobox thorium

Thorium,  ₉₀Th

General properties
Name, symbol	thorium, Th
Appearance	silvery, often with black tarnish
Pronunciation	/ˈθɔəriəm/ THAWR-ee-əm
Thorium in the periodic table
Ce ↑ Th ↓ (Uqb) actinium ← thorium → protactinium
Atomic number (Z)	90
Group, block	group n/a, f-block
Period	period 7
Element category	actinide
Standard atomic weight (±) (Ar)	232.0377(4)
Electron configuration	[Rn] 6d2 7s2
per shell	2, 8, 18, 32, 18, 10, 2
Physical properties
Phase	solid
Melting point	2023 K ​(1750 °C, ​3182 °F)
Boiling point	5061 K ​(4788 °C, ​8650 °F)
Density near r.t.	11.724 g/cm3
Heat of fusion	13.81 kJ/mol
Heat of vaporization	514 kJ/mol
Molar heat capacity	26.230 J/(mol·K)
vapor pressure 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
Electronegativity	Pauling scale: 1.3
Ionization energies	1st: 587 kJ/mol 2nd: 1110 kJ/mol 3rd: 1930 kJ/mol
Atomic radius	empirical: 179.8 pm
Covalent radius	206±6 pm
Miscellanea
Crystal structure	​face-centered cubic (fcc)
Speed of sound 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	157 nΩ·m (at 0 °C)
Magnetic ordering	paramagnetic
Young's modulus	79 GPa
Shear modulus	31 GPa
Bulk modulus	54 GPa
Poisson ratio	0.27
Mohs hardness	3.0
Vickers hardness	295–685 MPa
Brinell hardness	390–1500 MPa
CAS Number	7440-29-1
History
Naming	after Thor, the Norse god of thunder
Discovery	Jöns Jakob Berzelius (1829)
Most stable isotopes of thorium
iso NA half-life DM DE (MeV) DP 227Th trace 18.68 d α 6.038 5.978 223Ra 228Th trace 1.9116 y α 5.520 224Ra 229Th trace 7340 y α 5.168 225Ra 230Th trace 75400 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

These references will appear in the article, but this list appears only on this page.