Thallium is a chemical element with the symbol Tl and atomic number 81. It is a gray post-transition metal that is not found free in nature. When isolated, Tl 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. This element can be generated artificially. It can be obtained by smelting of lead and zinc. It is generally obtained as a by-product in the production of sulphuric acid.
|Melting point||303.5 °C (578.3 °F)|
|Boiling point||1,457 °C (2,655 °F)|
Uses of Thallium
Commercially, It is produced not from potassium ores, but as a byproduct from refining of heavy-metal sulfide ores. Approximately 60–70% of thallium production is used in the electronics industry, and the remainder is used in the pharmaceutical industry and in glass manufacturing. In ancient times it was used as a rat poison and as an ant killer. Thallium compounds are used in the manufacture of glasses. It is used in photocells. It is used in the production of infrared optics. It is also used in infrared detectors. The radioisotope thallium-201 (as the soluble chloride TlCl) is used in small amounts as an agent in a nuclear medicine scan, during one type of nuclear cardiac stress test.
Properties of Thallium
- It melts easily.
- Tl Salts that are soluble are generally toxic. They are merely tasteless.
- It oxidizes at +3 and +1 oxidation states forming ionic salts.
- There are several Tl compounds wherein Tl(III) resembles the aluminum (III) compounds.