Thorium

Thorium (Th)

Grey radioactive metallic element. Belongs to actinoids. Found in monazite sand in Brazil, India and the US. Thorium-232 has a half-life of 1.39x10^10 years. Can be used as a nuclear fuel for breeder reactors. Thorium-232 captures slow Neutrons and breeds uranium-233. Discovered by Jons J. Berzelius in 1829.
Atomic Number90
Atomic Weight232.0377
Mass Number232
Group
Period7
Blockf
Protons90 p+
Neutrons142 n0
Electrons90 e-
Thorium sample 0.1g.jpg Animated Bohr Model Enhanced Bohr Model Bohr Model Orbital Diagram

Properties

Atomic Radius
180 pm
Atomic Volume
Covalent Radius
175 pm
Metallic Radius
Ionic Radius
94 pm
Crystal Radius
108 pm
Van der Waals radius
245.00000000000003 pm
Density
11.7 g/cm³
Boiling Point
5,060 K
Melting Point
2,028 K
Electrons per shell2, 8, 18, 32, 18, 10, 2
Electronegativity
1.3
Electrophilicity
Proton Affinity
Electron Affinity
Ionization Potential
Heat of Vaporization
513.7 kJ/mol
Heat of Fusion
16.11 kJ/mol
Heat of Formation
602 kJ/mol
Molar Heat Capacity
27.32 J/(mol K)
Specific Heat Capacity
0.118 J/(g⋅K)
Thermal Conductivity
Gas Basicity
Dipole Polarizability
217 a₀
C6 Dispersion Coefficient
Oxidation States2, 3, 4
Color
Silver
Crystal StructureFace Centered Cubic (FCC)
Lattice Constant
5.08 Å
Bulk Modulus
Electrical Resistivity
Electron Configuration[Rn] 6d2 7s2
Magnetic Ordering
Magnetic Susceptibility
PhaseSolid
Poisson Ratio
Shear Modulus
Young's Modulus
Allotropes
Alternate Names
Adiabatic Index
Appearance
Electric Conductivity
Critical Pressure
Critical Temperature
Curie Point
Electrical
Hardness
Magnetic Susceptibility
Magnetic
Neel Point
Neutron Cross Section
Neutron Mass Absorption
Gas Phase
Quantum Numbers
Refractive Index
Space Group
Speed of Sound
Superconducting Point
Thermal Expansion
Valence Electrons
Classification
CategoryActinides, Actinides
CAS Group
IUPAC Group
Glawe Number34
Mendeleev Number16
Pettifor Number47
Geochemical Classrare earth & related
Goldschmidt Classlitophile
Radioactivity
RadioactiveYes ☢️
Decay Mode
Half-Life
Lifetime
Abundance
Abundance in Earth's crust
9.6 mg/kg
Abundance in Oceans
0.000001 mg/L
Abundance in Human Body
Abundance in Meteor
Abundance in Sun
Abundance in Universe4×10-8%

Isotopes of Thorium

Stable Isotopes
230Th 232Th
Unstable Isotopes
209Th 210Th 211Th 212Th 213Th 214Th 215Th 216Th 217Th 218Th 219Th 220Th 221Th 222Th 223Th 224Th 225Th 226Th 227Th 228Th 229Th 231Th 233Th 234Th 235Th 236Th 237Th 238Th

History

Thorium was discovered by Jöns Jacob Berzelius in 1828, in Stockholm, Sweden. Thorium was first observed to be radioactive in 1898, independently, by Polish-French physicist Marie Curie and German chemist Gerhard Carl Schmidt. The crystal bar process was discovered by Anton Eduard van Arkel and Jan Hendrik de Boer in 1925 to produce high-purity metallic thorium. Named after Thor, Scandinavian god of war

DiscoverersJöns Berzelius
Discovery LocationSweden
Discovery Year1828
Name OriginNamed for Thor, Norse god of thunder.
Thorium is highly radioactive
Thorium fuel research is continuing in several countries including the USA and India

Uses

Thorium is used to coat tungsten filaments in light bulbs. It is also used in its oxide form in gas tungsten arc welding to increase the high-temperature strength of tungsten electrodes and improve arc stability. Thorium-magnesium alloys are used in the aerospace industry for aircraft engines. Used in making strong alloys. Also in ultraviolet photoelectric cells. It is a common ingredient in high-quality lenses. Bombarded with neutrons make uranium-233, a nuclear fuel.

Sources

Found in various minerals like monazite and thorite.