Symbol Tm
Atomic Number 69
Atomic Mass 168.93 g.mol -1
Discovered by Per Theodor Cleve in 1879

Chemical Properties of Thulium

Group Lanthanides Melting point 1545°C, 2813°F, 1818 K
Period 6 Boiling point 1950°C, 3542°F, 2223 K
Block f Density (g cm−3) 9.32
Atomic number 69 Relative atomic mass 168.934
State at 20°C Solid Key isotopes 169Tm
Electron configuration [Xe] 4f136s2 CAS number 7440-30-4
ChemSpider ID 22400 ChemSpider is a free chemical structure database

What is Thulium?

  • Thulium is a chemical element having an atomic number 69 with the symbol Tm, discovered by Theodor Cleve in the year 1879.
  • It is the thirteenth element in the lanthanide series in the periodic table.
  • The element is barely traced purely in nature but it is traced in minute amounts in minerals with other rare earth metals.

Uses of Thulium

  • It is used for laser manufacturing and for surgical purposes.
  • Thulium is used as a source of radiation from portable X-ray devices and in nuclear reactions.
  • Despite being slightly expensive, superconductors of high temperature use thulium.
  • It is used for manufacturing ferrites, ceramic magnetic materials for microwave items.

Properties of Thulium

  • The element is the second least abundant element in the lanthanide series.
  • It would tarnish once exposed to air due to its malleability and ductility.
  • The element contains one natural isotope, 169Tm which has a half-life of 1.92 years.
  • The remaining isotopes of the element have a half-life that ranges from 2 minutes to 64 hours.

Certain Facts About Thulium

  • Natural thulium in ceramic magnetic materials is used in microwave equipment and are useful for doping fiber lasers.
  • Once used for bombarding in a nuclear reactor, thulium could be employed as a radiation source in portable X-ray equipment.
  • Unlike the other lanthanides, thulium has a low-to-moderate acute toxic rating.

Practise This Question

Manganese is a transition element because _____________.