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Thallium 81Tl204.37
Discovered in 1861 by William Crookes at London, England. Isolated in 1862 by C.A. Lamy at Paris, France.
[Greek: thallos = green twig]
French: thallium
German: Thallium
Italian: tallio
Spanish: talio
Description: Thallium is
a soft, silvery-white metal, which tarnishes readily in moist air and reacts
with steam to form TIOH. It is attacked by acids, rapidly so by HNO3. Thallium
is little used because of its toxicity, but is still employed in special types of glass.
Materials properties
| Density: |
11 850 kg/m-3 [293 K]; 11 290 [liquid at m.p.] |
| Melting point: |
576.7 °K |
| Boiling point: |
1730 °K |
| Molar volume: |
17.24 cm3 |
| Thermal conductivity: |
46.1 [300 K] Wm-1K-1 |
| Coefficient of linear thermal expansion: |
28 x 10-6 K-1 |
| Electrical resistivity: |
18 x 10-8 [273 K] Wm |
| Mass magnetic susceptibility: |
-3.13 x 10-9(s) kg-1m3 |
| Young's modulus: |
7.90 GPa |
| Rigidity modulus: |
2.71 GPa |
| Bulk modulus: |
28.5 GPa |
| Poisson's ratio: |
0.45 GPa |
| Radii: |
Tl3+ 105; Tl+149; atomic 170; covalent 155 |
| Electronegativity: |
1.62 (TlI ) 2.04 (TlIII) (Pauling); 1.44 (Allred); 3.2 eV (absolute) |
| Effective nuclear charge: |
5.0 (Slater); 12.25 (Clementi); 13.50 (Froese-Fischer) |
| Number of Isotopes (incl. nuclear isomers): |
41 |
| Issotope mass range: |
184 -> 210 |
Biological data
| Biological role: |
None. |
| Toxicity |
|
| Toxic intake: |
metal,oral,human = 5.7 mg kg -1 |
| Lethal intake: |
ingestion of 0.2 - 1 g Tl2SO4 for humans. LD 50 (Tl2SO4, oral, mouse) = 29 mg kg -1 |
| Hazards: |
Thallium compounds are extremely toxic and cumulative; they are also absorbed through the skin. Thallium takes several days to act and affects the nervous system. It is also teratogenic.
|
| Level in humans |
|
| Blood: |
0.00048 mg dm-3 |
| Bone: |
0.002 p.p.m. |
| Liver: |
0.004 - 0.033 p.p.m. |
| Muscle: |
0.07 p.p.m. |
| Daily dietary intake : |
0.0015 mg |
| Total mass of element in average [70 kg] person: |
0.5 mg |
Crystal data
| Crystal structure, (cell dimentions / pm), space group |
α-Tl hexagonal (a = 345.6, c=552.6),
P63/mmc β-Tl cubic (a=388.2), Im3m γ-Tl f.c.c. (a=485.1), Fm3m T(α->β) = 503 K |
| X-ray diffraction: mass absorption coefficients (µ/ρ)/cm2g-1: |
CuKα 224 MoKα 119 |
| Neutron scattering length, b/10-12cm: |
0.8776 |
| Thermal neutron capture cross-section, σa/barns : |
3.43 |
Geological data
| Minerals: |
Thallium minerals are rare, but the element is dispersed in potassium minerals such as sylvite and the caesium mineral pollucite. |
| Mineral |
Formula |
Density |
Hardness |
Crystal apperance |
| Crookesite |
Cu7TlSe4 |
6.9 |
2.5 - 3 |
tet., metallic grey |
| Hutchinsonite |
(Tl,Pb)2As5S9 |
4.6 |
1.5 - 2 |
orth., adam. red. |
| Lorandite |
TlAsS2 |
5.53 |
2 - 2.5 |
mon., met. adamantine red/grey |
| Thalcusite |
Cu3FeTl2S4 |
6.54 |
2.5 |
tet., metallic grey |
| Chief ore: |
Thallium is generally obtained as the by-product of zinc and lead smelting. |
| World production: |
30 tonnes/year |
| Main mining areas: |
see zinc and lead. |
| Reserves: |
n.a. |
| Specimen: |
available as granules. Danger! |
| Abundances |
|
| Sun: |
8.0 (relative to H = 1 x 1023) |
| Earth's crust: |
0.6 p.p.m. |
| Seawater: |
1.4 x 10-5 p.p.m. |
| Residence time: |
10 000 years |
| Classification: |
accumulating |
| Oxidation state: |
I |
Other sizes and specifications on request
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