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.
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Indo-European & Semitic Roots Appendices
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