thallium

American  

[thal-ee-uhm] / ˈθæl i əm /

noun

Chemistry.

1. a soft, malleable, rare, bluish-white metallic element: used in the manufacture of alloys and, in the form of its salts, in rodenticides. Tl; 204.37; 81; 11.85 at 20°C.

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thallium British  

/ ˈθælɪəm /

noun

1. 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

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thallium Scientific  

/ thăl′ē-əm /

1. 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.

2. See Periodic Table

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Etymology

Origin of thallium

1860–65; < New Latin, equivalent to thall- (< Greek thallós green stalk) + -ium -ium; named after green line in its spectrum

Example Sentences

See Examples For:

thallium

The 8th century Katla eruption created a 12-year spike in metals like bismuth and thallium in Greenland ice cores.

From Science Daily ● Mar. 20, 2026

The thallium isotope ratios showed the global ocean lost oxygen overall during the last ice age compared to the current warmer interglacial period.

From Science Daily ● Jan. 21, 2024

Lepidolite extraction and smelting produces toxic by-products like thallium and tantalum that cause severe water pollution, said Wu Wei, an assistant professor at Xiamen University.

From Reuters ● Jun. 15, 2023

A female relative of Miyamoto's, who was hospitalised in Kyoto since July 2020 and is now unconscious, was also found to have ingested thallium.

From BBC ● Mar. 27, 2023

Indeed, the silver bands have wonderfully degenerated since the bit of thallium was put in, and for a reason worth knowing.

From Six Lectures on Light Delivered In The United States In 1872-1873 by Tyndall, John