Thallium

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, thallium resembles tin, but discolors when exposed to air.

Properties

Thallium is soft and malleable and has a low melting point. It is a highly toxic metal with many uses.

History

Thallium was discovered by William Crookes in 1861. He noticed the new green spectral line and concluded that a new element was present. Later, Claude-Auguste Lamy used a spectrometer that was similar to Crookes to determine the properties of the new element.

Occurrence

Thallium is not a rare element; it is 10 times more abundant than silver. The metal is found in the ores of many minerals but is not found as a free element.

Applications

The main source of thallium for practical purposes is the byproduct of refining heavy metal sulfide ores. Thallium is also used in electronic devices, switches, and closures, primarily for its electrical conductivity.

Health effects

Thallium and its compounds are extremely toxic, and contact with skin is dangerous. Thallium poisoning can occur through skin contact, inhalation, or ingestion.

See also

• List of chemical elements
• Periodic table

External links

• WebElements.com – Thallium

Thallium Resources
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