Thulium is a chemical element that has the atomic number 69. It has an atomic mass of 168.934 g/mol. It is represented by the symbol Tm. Thulium is a member of the lanthanide series and can be found in period 6 of the periodic table. It is an f-block element. There are 69 protons, 69 electrons and 100 neutrons in an electrically neutral atom of Thulium. The electronic configuration of Thulium is 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p6 4f13 5d0 6s2. The oxidation states of Thulium are 0, +2, +3, and electronegativity is 1.25 (Pauling scale). Thulium has 34 radioisotopes and only one naturally stable isotope Tm-169. Thulium has two major allotropes; tetragonal α-Tm and hexagonal β-Tm.
At STP thulium is solid and has a density of 9.32 g/cm3. Its melting point is 1818 K ?(1545 °C, ?2813 °F) and its boiling is 2223 K ?(1950 °C, ?3542 °F).
The pure metal of Thulium has a silvery-grey appearance that tarnishes when exposed to air. The Thulium metal is ductile and malleable and can be cut with a knife. Thulium was discovered and isolated by Swedish chemist Per Teodor Cleve in 1879.
Thulium is the second least abundant lanthanide after promethium. It could be found in trace amounts with other rare earth elements. Thulium can be found in minerals such as gadolinite, xenotime, euxenite, and monazite. Thulium makes approximately 0.5 ppm of soil. Most of its ores are found in China. Some deposited are found in countries like the United States, Greenland, India, Tanzania, Australia, and Brazil. It is the least abundant lanthanide metal after radioactive promethium.
It is used in high-temperature superconductors. It is used in the X-ray machine and in lasers as Holmium-chromium-thulium triple-doped. Thulium is used in euro banknotes because thulium fluoresces with a blue color which is useful against counterfeiting.
What is thulium used for?
The following are some of the uses of Thulium and its compounds:
- Electronics:
Thulium is used in high-temperature superconductors. It is also used in magnetic material which is used in microwave equipment.
- Used as Fluorescence:
Thulium is used in euro banknotes as a measure against counterfeiting. Thulium interacts with a blue colour when exposing to ultraviolet.
- Used as a source X-ray:
Thulium-170 is used in portable X-ray devices. the isotopes Thulium-170 has a half-life of 128.6 days which makes it a popular radiation source for use in industrial radiography.
- Used in Laser:
Holmium-chromium-thulium triple-doped yttrium aluminium garnet is a laser medium material used for high efficiency. Thulium-based lasers are very efficient for the superficial ablation of tissue.
When was thulium discovered?
Thulium was discovered and isolated by Swedish chemist Per Teodor Cleve in 1879.
Where is thulium found?
Thulium is a rare earth element and it is the least abundant lanthanide after promethium which is a radioactive element. It could be found in minerals with other rare earth elements. It is found in trace amounts in minerals like euxenite, monazite, xenotime and gadolinite. Large deposits of these minerals are in China. And can be found in countries like Australia, Brazil, Greenland, India, Tanzania, and the United States.
