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Caesium (Cs)
We are a leading manufacturer and supplier of research materials
Cesium 55Cs132.905
Discovered in 1860 by R. Bunsen und G.R. Kirchhoff at Heidelberg, Germany.
[Latin, caesius = sky bluw]
French: césium
German: Caesium
Italian: cesio
Spanish: cesio
Description: Caesium/Cesium (US) is a soft, shiny, gold-coloured metal which oxidises repidly in air and reacts explosively with water. It is obtained by the electrolysis of molten caesium cyanide, and by other methods. Caesiumand its salts are used commercially as catalyst promoters, in special glasses, and in radiation monitoring equipment.
Further Materials properties
| Crystal structure: | (cell dimensions/pm), space group, b.c.c. (78 K) (a=614), Im3m High pressure forms: (a= 598.4), Fm3m; (a=580.0), Fm3m |
|---|---|
| X-ray diffractions mass absorption coefficients: | CuKa 318 (µ/r) / cm2g-1 MoKa 41.3 (µ/r) / cm2g-1 |
| Neutron scattering length: | 0.542 b/10-12 cm |
| Thermal neutron capture cross-section: | 29 sa / barns |
| Density: | 1873 kg/m-3 [293 K]; 1843[liquid at m.p.] |
| Melting point: | 28.4°C / 301,55°K |
| Boiling point: | 678.45°C / 951.6°K |
| Molar volume: | 70.96 cm3 |
| Thermal conductivity: | 35.9 [300 K] W m-1K-1 |
| Coefficient of linear thermal expansion: | 97 x 10-6 K-1 |
| Electrical resistivity: | 20.0 x 10-8 [293 K] Ωm |
| Mass magnetic susceptibility: | +2.8 x 10-8(s) kg-1m3 |
| Young's modulus: | 1.7 GPa |
| Rigidity modulus: | 0.65 GPa |
| Bulk modulus: | n.a. |
| Poisson's ratio: | 0.295 GPa |
| Radi: | Cs+ 165; atomic 265.4; covalent 235; van der Waals 262 |
| Electronegativity: | 0.79 (Pauling); 0.86 (Allred); 2.18 eV (absolute) |
| Effective nuclear charge: | 2.20 (Slater); 6.36 (Clementi); 8.56 (Froese-Fischer) |
| Number of Isotopes (incl. nuclear isomers): | 40 |
| Isotope mass range: | 114 -> 145 |
Biological data
| Biological role: | No known biological role, but it may partly replace potassium |
|---|---|
| Toxicity | |
| Toxic intake: | n.a. but regarded as fairly toxic |
| Lethal intake: | LD50 (Cs2CO3, oral, rat) = 2333 mg Kg-1 |
| Hazards: | Although similar to potassium, caesium can have serious effects on the body if taken in excess. Rats fed Cs in place of K died after two weeks. 134Cs and 137Cs are dangerous radioactive pollutants which have escaped from nuclear reactors. |
| Level in humans | |
| Blood: | 0.0038 mg dm-3 |
| Bone: | 0.013 - 0.052 ppm |
| Liver: | 0.04 - 0.05 ppm |
| Muscle: | 0.07 - 1.6 ppm |
| Daily dietary intake: | 0.004 - 0.03 mg |
| Total mass of element in average [70 kg] person: |
c. 6 mg |
Geological data
| Minerals: | Few are known | |||
|---|---|---|---|---|
| Mineral | Formula | Density | Hardness | Crystal apperance |
| Cesium kupleskite | Cs3(Mn,Fe)7(Ti,Nb)2Si8O24.(OH,F)7 | 3.68 | 4 | tric., dull gold-brown |
| Pollucite | (Cs,Na)2Al2Si4O12.nH2O | 2.94 | 6.5 | cub., col., vit. |
| Chief ores: | pollucite; cesium is also found in lepidolite (see lithium) |
|---|---|
| World production: | c. 20 (cesium compounds) tonnes/year |
| Main mining areas: | Bernic Lake (Manitoba, Canada), Bikita (Zimbabwe) and South-West Africa |
| Reserves: | c. 100 000 (60 000 at Bernic Lake) |
| Specimen: | available as small ingots in sealed ampoules. Danger! |
| Abundances | |
|---|---|
| Sun: | <80 (relative to H = 1 x 1012) |
| Earth's crust: | 3 ppm |
| Seawater | 3.0 x 10-4 |
| Residence time: | 600 000 years |
| Classification: | accumulating |
| Oxidation state: | I |
Source: Emsley, J. (1998) The Elements (3rd Edition)
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