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

Density (g/cc): 11.78
Melting Point (K): 2028
Boiling Point (K): 5060
Appearance: Gray, soft, malleable, ductile, radioactive metal
Atomic Radius (pm): 180
Atomic Volume (cc/mol): 19.8
Covalent Radius (pm): 165
Ionic Radius: 102 (+4e)
Specific Heat (@20C J/g mol): 0.113
Fusion Heat (kJ/mol): 16.11
Evaporation Heat (kJ/mol): 513.7
Thermal Conductivity (@25C W/m K):
Debye Temperature (K): 100.00
Pauling Negativity Number: 1.3
First Ionizing Energy (kJ/mol): 670.4
Oxidation States: 4
Electronic Configuration: [Rn] 6d2 7s2
Lattice Structure: Face-Centered Cubic (FCC)
Lattice Constant (): 5.080
Lattice C/A Ratio: n/a

Mineral Hardness [no units]: 3.0
Brinell Hardness [/MN m-2]: 400
Vickers Hardness [/MN m-2]: 350

Note: Thorium is radioactive material, care is advised. Work should be carried out in glove boxes with proper ventilation or "hot cells" if critical radiation limit is surpassed. In any case, check radiation.

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