thallium(redirected from Element 81)
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n. Symbol Tl
A soft, malleable, highly toxic metallic element, used in photocells, infrared detectors, low-melting glass, and formerly in rodent and ant poisons. A radioactive isotope, Tl-201, is used in medical imaging. Atomic number 81; atomic weight 204.38; melting point 304°C; boiling point 1,473°C; specific gravity 11.85 (20°C); valence 1, 3. See Periodic Table.
(Elements & Compounds) a soft malleable highly toxic white metallic element used as a rodent and insect poison and in low-melting glass. Its compounds are used as infrared detectors and in photoelectric cells. Symbol: Tl; atomic no: 81; atomic wt: 204.3833; valency: 1 or 3; relative density: 11.85; melting pt: 304°C; boiling pt: 1473±10°C
[C19: from New Latin, from Greek thallos a green shoot; referring to the green line in its spectrum]
thal•li•um(ˈθæl i əm)
a soft, malleable, rare, bluish white metallic element: used in the manufacture of alloys and, in the form of its salts, in rodenticides. Symbol: Tl; at. wt.: 204.37; at. no.: 81; sp. gr.: 11.85 at 20°C.
[1861; < Greek thall(ós) green stalk + -ium2; after the green line in its spectrum]
Symbol Tl A soft, easily shaped, very poisonous metallic element that has a low melting temperature. It is used in photography, in making low-melting and highly refractive glass, and in treating skin infections. Atomic number 81. See Periodic Table.
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|Noun||1.||thallium - a soft grey malleable metallic element that resembles tin but discolors on exposure to air; it is highly toxic and is used in rodent and insect poisons; occurs in zinc blende and some iron ores|
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.