Thulium
Atomic Number: 69
Symbol: Tm
Atomic Weight: 168.93421
Discovery: Per Theodor Cleve 1879 (Sweden)
Electron Configuration: [Xe] 4f13 6s2
Element Classification: Rare Earth (Lanthanide)
Word Origin: Thule, ancient name of Scandinavia.
Density (g/cc): 9.321
Melting Point (K): 1818
Boiling Point (K): 2220
Appearance: soft, malleable, ductile, silvery metal
Atomic Radius (pm): 177
Atomic Volume (cc/mol): 18.1
Covalent Radius (pm): 156
Ionic Radius: 87 (+3e)
Specific Heat (@20°C J/g mol): 0.160
Evaporation Heat (kJ/mol): 232
Pauling Negativity Number: 1.25
First Ionizing Energy (kJ/mol): 589
Oxidation States: 3, 2
Lattice Structure: Hexagonal
Lattice Constant (Å): 3.540
Lattice C/A Ratio: 1.570
References: Los Alamos National Laboratory (2001), Crescent Chemical Company (2001), Lange's Handbook of Chemistry (1952), CRC Handbook of Chemistry & Physics (18th Ed.)
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