Strontium (Sr)

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Strontium 38Sr87.62


1790 von A. Crawford in Edingburg, Schottland, als Element erkannt. 1808 von Sir Humphry Davy in London, UK, dargestellt.

[Nach Strontian, Schottland, benannt]

French: strontium
English: strontium
Italian: stronzio
Spanish: estroncio


Beschreibung: Silberweißes, weiches Metall, das man durch Reduktion von SrO mit Al bei hohen Temperaturen erhält. Kompaktes Metall wird durch eine Oxidhaut geschützt, aber es verbrennt an Luft und reagiert mit Wasser. Verwendung in Spezialgläsern und in der Pyrotechnik, um Rotfärbung zu erzeugen.

  


Further Materials properties

 

Crystal structure:

(cell dimensions/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 diffractions mass absorption coefficients: CuKa 125 (µ/r) / cm2g-1
MoKa 95.0 (µ/r) / cm2g-1
Neutron scattering length: 0.702 b/10-12 cm
Thermal neutron capture cross-section: 1.28 sa / barns
Density: 2540 kg/m-3 [293 K]; 2375 [liquid at m.p.]
Melting point: 768.85°C / 1042°K
Boiling point: 1383.85°C / 1657°K
Molar volume: 34.50 cm3
Thermal conductivity: 35.3 [300 K] W m-1K-1
Coefficient of linear thermal expansion: 23 x 10-6 K-1
Electrical resistivity: 23.0 x 10-8 [295 K] Ωm
Mass magnetic susceptibility: +1.32 x 10-8(s) kg-1m3
Radi: 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
Isotope mass range: 79 -> 98

 

 


Biological data

 

Biological role: None.
Toxicity
Toxic intake: not regarded as toxic
Lethal intake: LD50 (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 ppm
Liver: 0.05 - 0.36 ppm
Muscle: 0.12 - 0.35 ppm
Daily dietary intake: 0.8 - 5 mg 
Total mass of element in average
[70 kg] person:
320 mg

 

Geological data

 

Minerals:
MineralFormulaDensityHardnessCrystal apperance
Clestite*  SrSO4 3.97  3 - 3.5  orth., vit./ colourless-pale blue
Strontianite  SrCO3 3.76  3.5  orth., vit./ resinous colourless

Chief ores:  celestite, strontianite
World production:  137 000 (strontium ores) tonnes/year
Producing 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 1012)
Earth's crust: 370 ppm
Seawater
Atlantic surface: 7.6 ppm
Atlantic deep: 7.7 ppm
Pacific surface: 7.6 ppm
Pacific deep: 7.7 ppm
Residence time: 4 x 10years
Classification: recycled
Oxidation state: II

  Source: Emsley, J. (1998) The Elements (3rd Edition)

Other sizes and specifications on request


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