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Thulium Facts

Chemical & Physical Properties of Thulium


This is a photo of ultrapure crystalline thulium.

This is a photo of ultrapure crystalline thulium which was prepared using sublimation. Thulium is a lustrous bright silvery-gray metal.

Jurii, Creative Commons License
Periodic Table of the Elements


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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