Thulium [Tm] (CAS-ID: 7440-30-4) locate me
An: 69 N: 100 Am: 168.93421
Group Name: Lanthanoid
Block: f-block  Period: 6 (lanthanoid)
State: solid at 298 K
Colour: silvery white Classification: Metallic
Boiling Point: 2223K (1950'C)
Melting Point: 1818K (1545'C)
Density: 9.32g/cm3
Shell Structure diagram | Atomic Radius diagram
Isotopes | More Info
Discovery Information
Who: Per Theodor Cleve
When: 1879
Where: Sweden
Name Origin
From Thule ancient name of Scandinavia.
Sources
Found with other rare earths in the minerals; monazite, gadolinite, euxenite, xenotime, and others.
Uses
None of thulium's compounds is commercially important mainly due to high production costs. Radioactive thulium is used to power portable x-ray machines, eliminating the need for electrical equipment.
Thulium-doped calcium sulphate (CaSO4) has been used in personal radiation dosimeters because it can register, by its fluorescence, especially low levels.
Notes
Thulium is the least abundant of the rare earth metals, is is and easy metal to work as it can be cut by a knife. Reserves of thulium are estimated to be about 105 tonnes. World production is about 50 tonnes per year as thulium oxide.
Thulium has a low-to-moderate acute toxic rating and should be handled with care. Metallic thulium in dust form presents a fire and explosion hazard.
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