thulium

Name thulium
Symbol Tm
Atomic Weight 168.93421
Atomic Number 69
CAS ID 7440-30-4
Group Number
Group Name Lanthanoid
Period Number 6
Origin of Name Named after Thule, ancient Scandinavia.
Year Discovered 1879
Discovery Credits Discovered by P. T. Cleve at Uppsala, Sweden.
Class Metallic
Color Silvery White
Standard State Solid at 77 F & 298 K
Description Silvery metal, rarest of the lanthanide group. Tarnishes in air and reacts with water. Few uses but some employed as a radiation source in portable x-ray equipment.

Diagnostic tests: 
There are no simple diagnostic tests to identify thulium.
X-ray fluorescence spectroscopy is commonly employed to identify and analyze members of the Rare-Earth group elements.

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