thallium
Sign in to saveThallium is a chemical element; it has symbol Tl and atomic number 81. It is a silvery-white post-transition metal that is not found free in nature. When isolated, thallium resembles tin, but discolors when exposed to air. Chemists William Crookes and Claude-Auguste Lamy discovered thallium independently in 1861, in residues of sulfuric acid production. Both used the newly developed method of flame spectroscopy, in which thallium produces a notable green spectral line. Thallium, from Greek , , meaning "green shoot" or "twig", was named by Crookes. It was isolated by both Lamy and Crookes in 18
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Thallium is a silvery-white metal element that doesn't occur naturally in pure form and was discovered in 1861 when chemists detected its distinctive green spectral line in sulfuric acid production residues. The element's name comes from its characteristic green color, and while it resembles tin in appearance, it tarnishes when exposed to air.
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Article
21 sectionsContents
- Characteristics
- Isotopes
- Compounds
- Thallium(III)
- Thallium(I)
- Organothallium compounds
- History
- Occurrence and production
- Applications
- Historic uses
- Optics
- Electronics
- High-temperature superconductivity
- Nuclear medicine
- Thallium stress test
- Other uses
- Toxicity
- See also
- Citations
- General bibliography
- External links
Thallium is a chemical element; it has symbol Tl and atomic number 81. It is a silvery-white post-transition metal that is not found free in nature. When isolated, thallium resembles tin, but discolors when exposed to air. Chemists William Crookes and Claude-Auguste Lamy discovered thallium independently in 1861, in residues of sulfuric acid production. Both used the newly developed method of flame spectroscopy, in which thallium produces a notable green spectral line. Thallium, from Greek , , meaning "green shoot" or "twig", was named by Crookes. It was isolated by both Lamy and Crookes in 1862, Lamy by electrolysis and Crookes by precipitation and melting of the resultant powder. Crookes exhibited it as a powder precipitated by zinc at the International Exhibition, which opened on 1 May that year.
Thallium tends to form the +3 and +1 oxidation states. The +3 state resembles that of the other elements in group 13 (boron, aluminium, gallium, indium). However, the +1 state, which is far more prominent in thallium than the elements above it in the periodic table, recalls the chemistry of alkali metals. Thallium(I) ions are found geologically mostly in potassium-based ores and (when ingested) are handled in many ways like potassium ions (K+) by ion pumps in living cells.