a rare, poisonous, bluish-gray, soft, metallic chemical element, used in making photoelectric cells, rat poisons, etc.: symbol, Tl; at. no. 81
Origin of thalliumModL: so named by Sir William Crookes, its discoverer ; from Classical Greek thallos, young, green shoot (; from thallein: see Thalia) because of its green spectral line
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.
Origin of thalliumthall(o)– (from its green spectral line) + –ium.
- A metallic chemical element (symbol Tl) with atomic number 81.
Coined based on Ancient Greek Î¸Î±Î»Î»ÏŒÏ‚ (thallos, “green branch") (after the color of the radiation spectra).