TRANSITION ELEMENT: LANTHANIDE
Atomic number: | 69 |
Group numbers: | 3 |
Period: | 6 |
Electronic configuration: | [Xe] 4f13 6s2 |
Formal oxidation number: | +3 |
Electronegativities: | 1.25 |
Atomic radius / pm: | 172.4 |
Relative atomic mass: | 168.934 22(2) |
Thulium was discovered by Per Theodore Cleve (SE) in 1879. Named after Thule, an ancient name for Scandinavia. It is a soft, malleable, ductile, silvery metal that tarnishes in air and reacts with water. Thulium dust is flammable. Thulium is found with other rare earths in the minerals gadolinite, euxenite, xenotime and monazite. Radioactive thulium is used to power portable x-ray machines, eliminating the need for electrical equipment. The price of 99.9 % pure thulium pieces is 291.00 € for 5 g.
Density / g dm-3: | 9321 | (293 K) |
Molar volume / cm3mol-1: | 18.12 | (293 K) |
Electrical resistivity / µΩcm: | 79 | (20 °C) |
Thermal conductivity / W m-1K-1: | 16.8 |
Melting point / °C: | 1545 |
Boiling point / °C: | 1950 |
Heat of fusion / kJ mol-1: | 18.4 |
Heat of vaporization / kJ mol-1: | 247 |
Heat of atomization / kJ mol-1: | 233.43 |
First ionization energy / kJ mol-1: | 596.70 |
Second ionization energy / kJ mol-1: | 1162.66 |
Third ionization energy / kJ mol-1: | 2284.79 |
in the atmosphere / ppm: | - |
in the Earth's crust / ppm: | 0.32 |
in the oceans / ppm: | 0.00000004 |
Crystal structure: | hexagonal |
Unit-cell dimensions / pm: | a=353.75, c=555.46 |
Space group: | P63/mmc |
Isotope | Relative atomic mass | Mass percent (%) |
---|---|---|
169Tm | 168.934211(3) | 100 |
Balanced half-reaction | Eo / V | |
---|---|---|
68 Erbium | ← | 69 Thulium | → | 70 Ytterbium |
Citing this page:
Generalic, Eni. "Thulium." EniG. Periodic Table of the Elements. KTF-Split, 18 Jan. 2024. Web. 5 Jan. 2025. <https://www.periodni.com/tm.html>.
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