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thuliumColumbia Encyclopedia entry: thulium
Thuliumthoo'lēəm [from Thule, an ancient name for Scandinavia], metallic chemical element; symbol Tm; at. no. 69; at. wt. 168.9342; m.p. about 1,545°C; b.p. 1,947°C; sp. gr. 9.3; valence +3. Thulium is a soft, malleable, ductile, lustrous silver-white metal. It is one of the rare-earth metals of the lanthanide series in Group 3 of the periodic table. It does not tarnish rapidly in dry air but should be protected from moisture. It forms compounds with oxygen and the halogens, most of which are light green. The oxide, Tm2O3, is called thulia. Thulium is the least abundant of the rare-earth metals. It is found in the minerals gadolinite and euxenite and in monazite, the chief commercial source. The metal can be obtained by chemical reduction of its compounds. The pure metal and compounds have few commercial uses, but they are often used without purification in combination with the other rare-earth metals and compounds, e.g., in lighter flints and carbon electrodes for arc lighting. Although the only naturally occurring isotope (thulium-169) is stable, there are 15 unstable isotopes. Thulium-170 (half-life about 129 days), prepared by irradiating thulium-169 in a nuclear reactor, emits X rays; it is used in portable X-ray sources. Thulium was discovered in 1879 by P. T. Cleve.
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Wikipedia search results for: Thulium
From Wikipedia, the free encyclopedia
Thulium is a chemical element that has the symbol Tm and atomic number 69. Thulium is the least abundant of the lanthanides. It is an easily workable metal with a bright silvery-gray luster. Despite its high price and rarity, thulium is used as radiation source in portable X-ray devices and in solid-state lasers.
Pure thulium metal has a bright, silvery luster. It is reasonably stable in air, but should be protected from moisture. The metal is soft, malleable, and ductile. Thulium is ferromagnetic below 32 K, antiferromagnetic between 32 and 56 K and paramagnetic above 56 K.
Thulium metal tarnishes slowly in air and burns readily at 150 °...more »
Columbia Encyclopedia search results: thulium
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- Periodic Table of the Elements: Thulium
Periodic Table of the Elements: ThuliumAtomic Number:69Atomic Symbol:TmThuliumAtomic Weight:168.9342ElectronConfiguration:2 · 8 · 1831 · 8 · 2
- Tm
Tm, chemical symbol for the element thulium.
- lanthanide series
Lanthanide series, a series of metallic elements, included in the rare-earth metals, in Group 3 of the periodic table. Members of the series are often called lanthanides, although lanthanum (a...
- Elements (table)
ElementsElementSymbolAtomic NumberAtomic Weight1Melting Point(Degrees Celsius)Boiling Point(Degrees Celsius)1 Parentheses indicate most stable isotope.actiniumAc89227.02781050.3200....
