Thallium
Thallium, element #81, has an atomic mass of 204.383 amu, a density of 11.85,
and electron levels of 2-8-18-32-18-3. It is a member of the boron group, with
valences of +1 and 3. Tl was discovered in 1861 by Sir William Crookes of England.
Tl melts at 303.85 degrees C and boils at 1472.85 degrees C. It is highly toxic, and is used
in rat and ant poisons, infrared radiation detectors, and diagnosing heart disease. Tl
poisoning can cause weakness, irritability, pain in arms and legs, confusion, mood
changes, hair loss, loss of vision, and permanent brain damage. (In other words, it would
NOT be a good idea to play with thallium.) Higher Tl exposures can cause
tremors, convulsions, hallucinations, coma, and death.
Tl is a solid, bluish-white metal. It occurs in the minerals crooksite, lorandite,
and hutchinsonite. There are only 2 natural Tl isotopes, but also 18 artificial.
June 19, 1997
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