Thorium
90
Th
Group
n/a
Period
7
Block
f
Protons
Electrons
Neutrons
90
90
142
General Properties
Atomic Number
90
Atomic Weight
232.03806
Mass Number
232
Category
Actinides
Colour
Silver
Radioactive
Yes
Named after Thor, Scandinavian god of war
Crystal Structure
Face Centered Cubic
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.
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.
Electrons per shell
2, 8, 18, 32, 18, 10, 2
Electron Configuration
[Rn] 6d2 7s2
Thorium fuel research is continuing in several countries including the USA and India
Physical Properties
Phase
Solid
Density
11.7 g/cm3
Melting Point
2115.15 K | 1842 °C | 3347.6 °F
Boiling Point
5061.15 K | 4788 °C | 8650.4 °F
Heat of Fusion
16 kJ/mol
Heat of Vaporization
530 kJ/mol
Specific Heat Capacity
0.113 J/g·K
Abundance in Earth's crust
0.0006%
Abundance in Universe
4×10-8%
Image Credits: Wikimedia Commons (NASA/ESA/JHU/R.Sankrit & W.Blair)
The Earth's thorium originated in the death throes of ancient stars
CAS Number
7440-29-1
PubChem CID Number
23960
Atomic Properties
Atomic Radius
179 pm
Covalent Radius
206 pm
Electronegativity
1.3 (Pauling scale)
Ionization Potential
6.3067 eV
Atomic Volume
19.9 cm3/mol
Thermal Conductivity
0.54 W/cm·K
Oxidation States
2, 3, 4
Applications
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.
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.
Thorium is highly radioactive
Isotopes
Stable Isotopes
232ThUnstable Isotopes
209Th, 210Th, 211Th, 212Th, 213Th, 214Th, 215Th, 216Th, 217Th, 218Th, 219Th, 220Th, 221Th, 222Th, 223Th, 224Th, 225Th, 226Th, 227Th, 228Th, 229Th, 230Th, 231Th, 233Th, 234Th, 235Th, 236Th, 237Th, 238Th