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Strontium 38Sr87.62
Strontium was recognized as an element in 1790 by A. Crawford at Edinburgh,
Scotland. Isolated in 1808 by Sir Humphry Davy at London, England.
[Named after Strontian, Scotland]
French: strontium
German: Strontium
Italian: stronzio
Spanish: estroncio
Description: Strontium
is a silvery-white, relatively soft metal that is obtained by heating strontium
oxide (SrO) with aluminium metal. The bulk metal is protected by an oxide
film, but it will burn in air if ignited, and is attacked by water. Strontium is
used in special glass for televisions and VDUs, and the red color of fireworks
and flares is produced by strontium salts.
Materials properties
| Density: |
2540 kg/m-3 [293 K]; 2375 [liquid at m.p.] |
| Melting point: |
1042 °K |
| Boiling point: |
1657 °K |
| Molar volume: |
34.50 cm3 |
| Thermal conductivity: |
35.3 [300 K] Wm-1K-1 |
| Coefficient of linear thermal expansion: |
23 x 10-6 K-1 |
| Electrical resistivity: |
2.3 x 10-8 [293 K] Wm |
| Mass magnetic susceptibility: |
+1.32 x 10-8(s) kg-1m3 |
| Young's modulus: |
15.7 GPa |
| Rigidity modulus: |
6.03 GPa |
| Bulk modulus: |
12.0 GPa |
| Poisson's ratio: |
0.28 GPa |
| Radii: |
Sr2+ 127; atomic 215(α-form); covalent 192 |
| Electronegativity: |
0.95 (Pauling); 0.99 (Allred); 2.0 eV (absolute) |
| Effective nuclear charge: |
2.85 (Slater); 6.07 (Clementi); 8.09 (Froese-Fischer) |
| Number of Isotopes (incl. nuclear isomers): |
23 |
| Issotope mass range: |
79 -> 98 |
Biological data
| Biological role: |
None. |
| Toxicity |
|
| Toxic intake: |
not regarded as toxic |
| Lethal intake: |
LD 50 (chloride, oral, rat) = 2250 mg kg -1 |
| Hazards: |
Strontium resembles calcium in metabolism and behaviour and is absorbed by the body and stored in the skeleton. This also happens with radioactive 90Sr which was produced by above-ground nuclear explosions in the 1950s and is widely disseminated in the environment.
|
| Level in humans |
|
| Blood: |
0.031 mg dm-3 |
| Bone: |
36 - 140 p.p.m. |
| Liver: |
0.05 - 0.36 p.p.m. |
| Muscle: |
0.12 - 0.35 p.p.m. |
| Daily dietary intake : |
0.8 - 5 mg |
| Total mass of element in average [70 kg] person: |
320 mg |
Crystal data
| Crystal structure, (cell dimentions / pm), space group |
α-Sr f.c.c. (a = 608.49), Fm3m
β-Sr h.c.p. (a=432, c=706), P63/mmc
γ-Sr b.c.c. (a=485), Im3m T(α -> β) = 506 K; T(β -> γ) = 813 K |
| X-ray diffraction: mass absorption coefficients (µ/ρ) /cm2g-1 : |
CuKα 125 MoKα 95.0 |
| Neutron scattering length, b/10-12cm: |
0.702 |
| Thermal neutron capture cross-section, σa/barns : |
1.28 |
Geological data
| Mineral |
Formula |
Density |
Hardness |
Crystal apperance |
| Celestite (celestine) |
SrSO4 |
3.97 |
3 - 3.5 |
orth.,, vit./colorless-pale blue |
| Strontianite |
SrCO3 |
3.76 |
3.5 |
orth., vit./resinous colorless |
| Chief ore: |
celestite, strontianite |
| World production: |
137 000 (strontium ores) tonnes/year |
| Main mining areas: |
UK, Tunisia, Russia, Germany, Mexico, USA |
| Reserves: |
n.a. |
| Specimen: |
available as granules and pieces.Warning! |
| Abundances |
|
| Sun: |
790 (relative to H = 1 x 1023) |
| Earth's crust: |
370 p.p.m. |
| Seawater: |
|
| Atlantic surface: |
7.6 p.p.m. |
| Atlantic deep: |
7.7 p.p.m. |
| Pacific surface: |
7.6 p.p.m. |
| Pacific deep: |
7.7 p.p.m. |
| Residence time: |
4 x 106 years |
| Classification: |
recycled |
| Oxidation state: |
II |
Other sizes and specifications on request
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