Topics Covered
Chemical Formula
Discovery
Basic Information
Occurrence
Isotopes
Production
Health Aspects
Key Properties
Applications
Reference
Chemical Formula
Tm
Discovery
Thulium was discovered by Per Teodor Cleve, a Swedish chemist, in 1879. Cleve discovered two new materials that were brown and green in color. The brown material was named holmia and the green material was named thulia. Cleve later discovered that thulia was thulium oxide.
Thulium comes from ‘Thule’, an ancient name for Scandinavia. Initially thulium was not found in its pure form but was available as a compound of thulium combined with other elements. Pure thulium was later produced by Charles James, an American scientist, in 1910.
Basic Information
|
Name |
Thulium |
|
Symbol |
Tm |
|
Atomic number |
69 |
|
Atomic weight |
168.93421 (2) |
|
Standard state |
Solid at 298 K |
|
CAS Registry ID |
7440-30-4 |
|
Group name |
Lanthanoid |
|
Period in periodic table |
6 (lanthanoid) |
|
Block in periodic table |
f-block |
|
Color |
Silvery white |
|
Classification |
Metallic |
|
Melting point |
1818 K (1545°C or 2813°F) |
|
Boiling point |
2223 K (1950°C or 3542°F) |
|
Density |
9.32 g/cm3 |
|
Phase at room temperature |
Solid |
Occurrence
Thulium is mostly found in monazite. The Earth’s crust also has large quantities of this element amounting to about 0.2 to 1 part per million. Thulium compounds also mix with other rare earth compounds in minerals such as gadolinite and euxenite.
Thulium (version 1) - Periodic Table of Videos
Isotopes
Thulium has 32 isotopes whose half-lives are known, with mass numbers 146 to 177. Thulium-169 is the only naturally occurring isotope of thulium.
Production
Pure thulium is produced by reducing TmF3 with calcium metal.
2TmF3 + 3Ca → 2Tm + 3CaF2
Key Properties
The key properties of thulium include:
-
It is a silvery metal that can be cut with a knife due it its soft texture.
-
It is easy to work with.
-
It is ductile and malleable.
-
It is stable in air.
-
It reacts rapidly with acids and slowly with water.
Applications
Thulium is useful in the following applications:
-
Lasers -Thulium lasers require less cooling and function very well at high temperatures and are used in satellites.
-
It is used in alloys along with other rare earth metals.
-
It is used to dope yttrium aluminum garnets (YAG) used in lasers.
-
It is used in euro banknotes because of its blue fluorescence under UV light that helps defeat counterfeiters.
Reference
http://www.webelements.com/helium/
http://education.jlab.org/itselemental/ele002.html
http://www.chemistryexplained.com/elements/C-K/Helium.html
http://www.lenntech.com/periodic/elements/he.htm
www.rsc.org/periodic-table/element/108/hassium
http://www.chemicool.com/elements/hassium.html
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