Thulium

Thulium (pronounced /ˈθjuːliəm/ THEW-lee-əm) is a chemical element that has the symbol Tm and atomic number 69. Thulium is the least abundant of the lanthanides (promethium is less abundant than thulium, but it is not found naturally on Earth). It is an easily workable metal with a bright silvery-gray luster. Despite its high price and rarity, thulium is used as radiation source in portable X-ray devices and in solid-state lasers. Pure thulium me... more

Thulium (pronounced /ˈθjuːliəm/ THEW-lee-əm) is a chemical element that has the symbol Tm and atomic number 69. Thulium is the least abundant of the lanthanides (promethium is less abundant than thulium, but it is not found naturally on Earth). It is an easily workable metal with a bright silvery-gray luster. Despite its high price and rarity, thulium is used as radiation source in portable X-ray devices and in solid-state lasers. Pure thulium metal has a bright, silvery luster. It is reasonably stable in air, but should be protected from moisture. The metal is soft, malleable, and ductile. Thulium is ferromagnetic below 32 K, antiferromagnetic between 32 and 56 K and paramagnetic above 56 K. Thulium metal tarnishes slowly in air and burns readily at 150 °C to form thulium(III) oxide: Thulium is quite electropositive and reacts slowly with cold water and quite quickly with hot water to form thulium hydroxide: Thulium reacts with all the halogens at temperatures. Reactions are slow at... less