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Calcium (Ca)
Wir sind führender Hersteller und Lieferant von Forschungsmaterialien
Calcium 20Ca40.078
1808 von Sir Humphry Davy in London, UK, dargestellt.
[Latin, calx = Kalkstein]
French: calcium
English: calzium
Italian: calcio
Spanish: calcio
Beschreibung: Silberweißes, relativ weiches Metall, das man früher durch Schmelzflußelektrolyse von Calciumchlorid erhielt, aber jetzt durch Erhitzen von CaO mit metallischem Aluminium im Vakuum gargestellt wird. Es wird durch eine Oxid/Nitridhaut geschützt und kann als Metall verarbeitet werden. Durch Sauerstoff und Wasser wird es angegriffen. Es wird für Legierungen und bei der Herstellung von Zr, Th, U und der Seltenerdmetalle verwendet. Kalk (CaO) wird in der Metallurgie, zur Wasseraufbereitung, in der chemischen Industrie, als Baustoff etc. verwendet.
Further Materials properties
| Crystal structure: | (cell dimensions/pm), space group, a-Ca f.c.c. (a=558.84), Fm3m β-Ca b.c.c. (a=448.0), Im3m γ-Ca h.c.p. (a=397, a=649), P62mmc [may contain H] T(a -> β) = 573 K; T (β -> γ) = 723 K |
|---|---|
| X-ray diffractions mass absorption coefficients: | CuKa 162 (µ/r) / cm2g-1 MoKa 18.3 (µ/r) / cm2g-1 |
| Neutron scattering length: | 0.476 b/10-12 cm |
| Thermal neutron capture cross-section: | 0.43 sa / barns |
| Density: | 1550.7 kg/m-3 [293 K]; 1365 [liquid at m.p.] |
| Melting point: | 838,85°C / 1112 °K |
| Boiling point: | 1483,85°C / 1757 °K (under pressure) |
| Molar volume: | 25.86 cm3 |
| Thermal conductivity: | 200 [300 K] W m-1K-1 |
| Coefficient of linear thermal expansion: | 22 x 10-6 K-1 |
| Electrical resistivity: | 3.43 x 10-8 [293 K] Ωm |
| Mass magnetic susceptibility: | +1.4 x 10-8(s) kg-1m3 |
| Young's modulus: | 19.6 GPa |
| Rigidity modulus: | 7.9 GPa |
| Bulk modulus: | 17.2GPa |
| Poisson's ratio: | 0.31 GPa |
| Radi: | Ca2+ 106; atomic 197 (a-form); covalent 174 |
| Electronegativity: | 1.00 (Pauling); 1.04 (Allred); 2.2 eV (absolute) |
| Effective nuclear charge: | 2.85 (Slater); 4.40 (Clementi); 5.69 (Froese-Fischer) |
| Number of Isotopes (incl. nuclear isomers): | 16 |
| Isotope mass range: | 36 -> 51 |
Biological data
| Biological role: | Essencial to all species |
|---|---|
| Toxicity | Non-toxic. |
| Toxic intake: | n.a. |
| Lethal intake: | LD50 (carbonate, oral, rat) = 6450 mg Kg-1 |
| Hazards: | Calcium compounds are only toxic via their other components |
| Level in humans | |
| Blood: | 60.5 mg dm-3 |
| Bone: | 170 000 ppm |
| Liver: | 100 - 360 ppm |
| Muscle: | 140 - 700 ppm |
| Daily dietary intake: | 600 - 1400 mg |
| Total mass of element in average [70 kg] person: |
1.00 kg |
Geological data
| Minerals: | Calcium occurs in many minerals. Below some main minerals. | |||
|---|---|---|---|---|
| Mineral | Formula | Density | Hardness | Crystal apperance |
| Anhydrate | CaSO4 | 2.98 | 3.5 | orth., vit./ pearly col. |
| Aragonite | CaCO2 | 2.947 | 3.5 - 4 | orth., vit. col.-white |
| Calcite | CaCO3 | 2.710 | 3 | orth. vit. col. (gem. onyx) |
| Dolomite | CaMg(CO3)2 | 2.85 | 3.4 - 4 | rhom., vit.col. |
| Chief ores: | calcite, dolomite, gypsum (used in cement and plaster) anhydrite (used to make H2SO4) |
|---|---|
| World production: | 2000 (calcium metal), 112 x 106 (lime, CaO) tonnes/year |
| Main mining areas: | comon everywhere |
| Reserves: | almost unlimited |
| Specimen: | available as granules, pieces or turnings. Care! |
| Abundances | |
|---|---|
| Sun: | 2.24 x 106 (relative to H = 1 x 1012) |
| Earth's crust: | 41 000 ppm |
| Seawater | |
| Altantic surface: | 390 ppm |
| Atlantic deep: | 430 ppm |
| Pacific surface: | 390 ppm |
| Pacific deep: | 440 ppm |
| Residence time: | 1 x 106 years |
| Classification: | recycled |
| Oxidation state: | II |
Source: Emsley, J. (1998) The Elements (3rd Edition)
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