INORGANIC CHEMISTRY A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z                    HOME ABOUT CATEGORIES SITE MAP COPYRIGHT ADVERTISE CONTACT entire Web this site thulium (Tm) Thulium. Image copyright: smart-elements.com A lustrous, silver-white, metallic element; it is the least abundant member of the lanthanide series. First discovered in 1879, its chief ore is monazite. Soft, malleable, and ductile, thulium combines with oxygen and the halogens. It is used in arc lighting; thulium-170, which emits X-rays, is used in portable X-ray units. Its most common isotope is 169Tm (100%). atomic number 69 relative atomic mass 168.934 relative density 9.31 melting point 1,545°C (2,813°F) boiling point 1,947°C (3,537°F) Related category    • INORGANIC CHEMISTRY Also on this site: Encyclopedia of Alternative Energy & Sustainable Living Encyclopedia of History Transport Concepts & Designs (partner site) BACK TO TOP