Atomic number: 69

Symbol: Tm

Category: lanthanoid metal

Density at 25°C: solid: density: 9.32 g·cm−3

This lanthenoid has found a potential use in making x-rays when it is changed into a radioactive isotope. The non-radioactive variety is also similar to other lanthenoids and used in laser applications.

remelted thulium metal sample. image: wikipedia

Use, natural applications or common combinations: 

  • potential x-ray production
  • lasers
  • possible uses in 'high' temperature super conductors.

Basic characteristics:

  • Standard atomic weight: 168.934 21(2)
  • Melting point:  1545 °C
  • Boiling point: 1950 °C
  • Radioactivity: most naturally stable
    • 170Tm is a  radioactive with a half life of 128.6 days
    • 171Tm with a half-life of 1.92 years