thulium

thu·li·um  (thl-m, thy-)

n. Symbol Tm

A bright, silvery rare-earth element obtained commercially from monazite, having an x-ray emitting isotope that is used in small portable medical x-ray units. Atomic number 69; atomic weight 168.934; melting point 1,545°C; boiling point 1,727°C; specific gravity 9.3; valence 2, 3. See Table at element.

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[After Thule¹.]

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thulium

Noun

Chem a silvery-grey element of the lanthanide series Symbol: Tm[after Thule, a region thought by ancient geographers to be northernmost in the world]

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thulium  (thl-m)

Symbol Tm

A soft, silver-gray metallic element of the lanthanide series. One of its artificial radioactive isotopes is used as a radiation source in small, portable x-ray machines. Atomic number 69; atomic weight 168.934; melting point 1,545°C; boiling point 1,727°C; specific gravity 9.3; valence 2, 3. See Periodic Table.

Thesaurus

Noun

1.

thulium - a soft silvery metallic element of the rare earth group; isotope 170 emits X-rays and is used in small portable X-ray machines; it occurs in monazite and apatite and xenotime atomic number 69, Tm metal, metallic element - any of several chemical elements that are usually shiny solids that conduct heat or electricity and can be formed into sheets etc. apatite - a common complex mineral consisting of calcium fluoride phosphate or calcium chloride phosphate; a source of phosphorus monazite - a reddish-brown mineral containing rare earth metals; an important source of thorium and cerium xenotime - a brown-to-yellow mineral that is a phosphate of yttrium in crystalline form