1860–65; < Neo-Latin, equivalent to thall- (< Greek thallós green stalk) + -ium -ium; named after green line in its spectrum
Based on the Random House Dictionary, © Random House, Inc. 2012.
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| of, pertaining to, or tending to develop into icelike crystals: glacial phosphoric acid |
| to heat intensely or roast |
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thallium
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thallium thal·li·um (thāl'ē-əm)
n.
Symbol Tl
A soft, malleable, highly toxic metallic element, used in photocells, infrared detectors, and low-melting glass. Atomic number 81; atomic weight 204.38; melting point 303.5°C; boiling point 1,473°C; specific gravity 11.85; valence 1, 3.
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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thallium  (thāl'ē-əm) Pronunciation Key
Symbol Tl A soft, malleable, very poisonous metallic element that is used in photography, in making low-melting and highly refractive glass, and in treating skin infections. Atomic number 81; atomic weight 204.38; melting point 303.5°C; boiling point 1,457°C; specific gravity 11.85; valence 1, 3. See Periodic Table. |
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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thallium
(Tl), chemical element, metal of main Group IIIa, or boron group, of the periodic table, poisonous and of limited commercial value. Like lead, thallium is a soft, low-melting element of low tensile strength. Freshly cut thallium has a metallic lustre that dulls to bluish gray upon exposure to air. The metal continues to oxidize upon prolonged contact with air, generating a heavy nonprotective oxide crust. Thallium dissolves slowly in hydrochloric acid and dilute sulfuric acid and rapidly in nitric acid.
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