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Iodine53I126.904
Discovered in 1811 by Bernard Courtois at Dijon, France.
[Greek: iodes = violet]
French: iode
German: Iod
Italian: iodio
Spanish: yodo
Description: Iodine is a
black, shiny, non-metallic solid (I2) which sublimes easily on
heating to give a purple vapour. It is used as a disinfectant, in
pharmaceuticals, food supplements, dyes, catalysts, and photography.
Materials properties
| Density: |
4390 kg/m-3 [293 K] |
| Melting point: |
386.7 °K |
| Boiling point: |
457.50 °K |
| Critical temperature: |
819 °K |
| Molar volume: |
25.74 cm3 |
| Thermal conductivity: |
0.449 [300 K] Wm-1K-1 |
| Coefficient of linear thermal expansion: |
n.a. |
| Electrical resistivity: |
1.37 x 107 [293 K] Wm |
| Mass magnetic susceptibility: |
-4.40 x 10-9(s) kg-1m3 |
| Radii: |
I- 196; covalent133; van der Waals 215 |
| Electronegativity: |
2.66 (Pauling); 2.21 (Allred); 6.76 eV (absolute) |
| Effective nuclear charge: |
7.60 (Slater); 11.61 (Clementi); 14.59 (Froese-Fischer) |
| Number of Isotopes (incl. nuclear isomers): |
37 |
| Issotope mass range: |
110 -> 140 |
Biological data
| Biological role: |
Most Iodine exists in nature as iodide ions, I-, the form in which it is taken into our bodies. Iodine is essential to many species, including humans. |
| Toxicity |
|
| Toxic intake: |
2 mg as I2. Iodides are similar in toxicity to bromides. |
| Lethal intake: |
human, oral = 2 g as I2.LD 50 (NaI, oral, rat) = 14 000 mg kg -1 |
| Hazards: |
Iodine in its elemental form, I2, is toxic, and its vapour irritates the eyes and lungs. The maximum allowable concentration when working with iodine is 1 mg m -3 in air |
| Level in humans |
|
| Blood: |
0.057 mg dm-3 |
| Bone: |
0.27 p.p.m. |
| Liver: |
0.7 p.p.m. |
| Muscle: |
0.05 - 0.5 p.p.m. |
| Daily dietary intake : |
0.1 - 0.2 mg |
| Total mass of element in average [70 kg] person: |
12 - 20 mg |
Crystal data
| Crystal structure, (cell dimentions / pm), space group |
orthorhombic (a=726.47, b=478.57, c=979.08), Cmca |
| X-ray diffraction: mass absorption coefficients (µ/ρ)/cm2g-1 : |
CuKα 294 MoKα 37.1 |
| Neutron scattering length, b/10-12cm: |
0.528 |
| Thermal neutron capture cross-section, σa/barns : |
6.2 |
Geological data
| Minerals: |
Minerals are very rare. Iodine cycles through the environment, and rain water contains about 0.7 p.p.b. |
| Mineral |
Formula |
Density |
Hardness |
Crystal apperance |
| Iodagyrite |
β-AgI |
5.69 |
1.5 |
hex., res./adam. colorless |
| Lautarite |
Ca(IO3)2 |
4.519 |
3.5 - 4 |
mon., col./yellow, transparent |
| Chief ore: |
from brines, which may have 50 p.p.m. of iodide, and the Chilean nitrate deposits which contain up to 0.3% calcium iodate. Some iodine is also extracted from seaweed. |
| World production: |
12 000 (elemental iodine) tonnes/year |
| Main mining areas: |
Chile, Japan |
| Reserves: |
2.6 x 106 tonnes |
| Specimen: |
available as crystals. Warning! |
| Abundances |
|
| Sun: |
n.a. |
| Earth's crust: |
0.14 p.p.m. |
| Seawater: |
|
| Atlantic surface: |
0.0489 p.p.m. |
| Atlantic deep: |
0.056 p.p.m. |
| Pacific surface: |
0.043 p.p.m. |
| Pacific deep: |
0.058 p.p.m. |
| Residence time: |
300 000 years |
| Classification: |
scavenged as I (-I), recycled as I (V) |
| Oxidation state: |
-I and V, mainly V |
Other sizes and specifications on request
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