The Element Thorium

In its pure form thorium will retain its luster on the silvery-white metal for several months. However, when it is exposed to oxygen, thorium slowly tarnishes in air, becoming grey and eventually black. It is widely known as a source of nuclear power and its been held responsible together with uranium for much of the internal heat of the earth.

Apart from its use in radioactive processes, thorium is used as an alloying element in magnesium; used to coat tungsten in electrical equipment; used in dating hominid fossils using Uranium-thorium age dating and also as a radiation shield.

Atomic Number & Chemical Properties

Element Basics:

Chemical Symbol: Th
Atomic Number: 90
Atomic Weight: 232.0381
Element Classification: Radioactive Rare Earth Element (Actinide Series)
Discovered By: Jons Jacob Berzelius
Date of Discovery: 1828 (Sweden)
Origin of Name: Named for Thor, Norse god of thunder.

How to Recognize it at a Party:

Gray, soft, malleable, ductile, radioactive metal

Seriously Atomic Information:

Density (g/cc): 11.78
Melting Point (°K): 2028
Boiling Point (°K): 5060
Atomic Radius (pm): 180
Atomic Volume (cc/mol): 19.8
Covalent Radius (pm): 165
Ionic Radius: 102 (+4e)
Pauling Negativity Number: 1.3
First Ionizing Energy (kJ/mol): 670.4
Oxidation States: 4
Electronic Configuration: [Rn] 6d2 7s2

Getting Intimate with Thorium:

Lattice Structure: Face-Centered Cubic (FCC)
Lattice Constant (Å): 5.080
Lattice C/A Ratio: n/a
Specific Heat (@20°C J/g mol): 0.113
Fusion Heat (kJ/mol): 16.11
Evaporation Heat (kJ/mol): 513.7
Thermal Conductivity (@25°C W/m K):
Debye Temperature (°K): 100.00

Society's Questions About Thorium:

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About the Element...

About the Chemical Elements:
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