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thallium 音標拼音: [θ'æliəm] n. 稀金屬元素,鉈符號Ti,原子序81 稀金屬元素,鉈符號Ti,原子序81 thallium n 1: 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 [synonym: {thallium}, {Tl}, {atomic number 81}] Thallium \Thal"li*um\, n. [NL., fr. Gr. ? young or green shoot or branch, twig. So called from a characteristic bright green line in its spectrum.] (Chem.) A rare metallic element of the aluminium group found in some minerals, as certain pyrites, and also in the lead-chamber deposit in the manufacture of sulphuric acid. It is isolated as a heavy, soft, bluish white metal, easily oxidized in moist air, but preserved by keeping under water. Symbol Tl. Atomic weight 203.7. [1913 Webster] thallium
Symbol: Tl Atomic number: 81 Atomic weight: 204.3833 Pure, unreacted thallium appears silvery-white and exhibits a metallic lustre. Upon reacting with air, it begins to turn bluish-grey and looks like lead. It is very malleable, and can be cut with a knife. There are two stable isotopes, and four radioisotopes, Tl-204 being the most stable with a half-life of 3.78 years. Thallium sulphate was used as a rodenticide. Thallium sulphine's conductivity changes with exposure to infrared light, this gives it a use in infrared detectors. Discovered by Sir William Crookes via spectroscopy. Its name comes from the Greek word thallos, which means green twig. Thallium and its compounds are toxic and can cause cancer.
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