Relative atomic mass: 204.3833 +- 0.0002

English: Thallium
French: Thallium
Croatian: Talij
German: Thallium
Italian: Tallio
Spanish: Talio

Atomic number: 81
Group numbers: 13
Period: 6
Standard state (20 oC): solid

Discovery: 1861 Sir William Crookes (GB)
Thallium was discovered by Sir William Crookes (GB) in 1861. The origin of the name comes from the Greek word thallos meaning green twig or green shoot. It is a soft grey metal that looks like lead and tarnishes in moist air. Thallium reacts in heated moist air and in acids. Its compounds are highly toxic by inhalation or ingestion and have a cumulative effect. Thallium is found in iron pyrites, in crookesite, hutchinsonite and lorandite. Most is recovered from the by-products of lead and zinc refining. Its compounds are used in rat and ant poisons and for detecting infrared radiation. The price of 99.999 % pure thallium granules is 566.70 for 500 g.
Electronic configuration: [Xe] 4f14 5d10 6s2 6p1
Formal oxidation number: +1 +3
Atomic radius: 170 pm

Electronegativities: 1.8
Thermal conductivity: 46.1 W/(m K)
Electrical resistivity (20 oC): 18 microOhm cm

Melting point: 304 oC
Boiling point: 1473 oC

Heat of fusion: 4.31 kJ/mol
Heat of vaporization: 166.1 kJ/mol
Heat of atomization: 182.845 kJ/mol

80Hg <= 81Tl => 82Pb

ASCII Periodic Table of the Elements
6 Jan. 2020
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