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Lanthanum 57La138.91
Discovered in 1839 by C.G. Mosander at Stockholm, Sweden.
[Greek: lanthanein =
to lie hidden]
French: lanthane
German: Lanthan
Italian: lantanio
Spanish: lantano
Description: Lanthanum
is a soft, silvery-white metal that rapidly tarnishes in air and burns easily if
ignited. It reacts with water to give hydrogen gas. Lanthanium is used in
optical glass and for flints. Lanthanium (III) salts are used as biological tracers for calcium.
Materials properties
| Density: |
6145 kg/m-3 [298 K] |
| Melting point: |
1194 °K |
| Boiling point: |
3730 °K |
| Molar volume: |
22.60 cm3 |
| Thermal conductivity: |
13.5 [300 K] Wm-1K-1 |
| Coefficient of linear thermal expansion: |
4.9 x 10-6 K-1 |
| Electrical resistivity: |
57 x 10-8 [293 K] Wm |
| Mass magnetic susceptibility: |
+1.1 x 10-8(s) kg-1m3 |
| Young's modulus: |
37.9 GPa |
| Rigidity modulus: |
14.9 GPa |
| Bulk modulus: |
n.a. |
| Poisson's ratio: |
0.28 GPa |
| Radii: |
La3+ 122; atomic 188; covalent 169 |
| Electronegativity: |
1.10 (Pauling); 1.08 (Allred); 3.1 eV (absolute) |
| Effective nuclear charge: |
2.85 (Slater); 9.31 (Clementi); 10.43 (Froese-Fischer) |
| Number of Isotopes (incl. nuclear isomers): |
26 |
| Issotope mass range: |
125 -> 149 |
Biological data
| Biological role: |
None. |
| Toxicity |
|
| Toxic intake: |
n.a. |
| Lethal intake: |
LD50(chloride, oral, rat) = 4200 mg kg-1 |
| Hazards: |
Lanthanium is mildly toxic by ingestion, and causes liver injury. |
| Level in humans |
|
| Blood: |
n.a. |
| Bone: |
< 0.08 p.p.m. |
| Liver: |
0.3 p.p.m. |
| Muscle: |
0.0004 p.p.m. |
| Daily dietary intake : |
n.a. but very low |
| Total mass of element in average [70 kg] person: |
c. 0.8 mg |
Crystal data
| Crystal structure, (cell dimentions / pm), space group |
α-La hexagonal (a = 377.0, c= 121.59), P63/mmc β-La f.c.c. (a=529.6), Fm3m γ-La b.c.c. (a=426), Im3m T(α->β)= 583 K; T(β->γ) = 1137 K |
| X-ray diffraction: mass absorption coefficients (µ/ρ)/cm2g-1: |
CuKα 341 MoKα 45.8 |
| Neutron scattering length, b/10-12cm: |
0.824 |
| Thermal neutron capture cross-section, σa/barns: |
8.98 |
Geological data
| Mineral |
Formula |
Density |
Hardness |
Crystal apperance |
| Allanite |
Ca(Ce,La)(Al,Fe)3(SiO4)3OH |
4.0 |
5.5 - 6 |
mon., sub-met. black |
| Bastnäsite-La* |
(La,Ce,etc.)CO3(F,OH) |
n.a. |
n.a. |
hex. |
| Cerite |
(Ce,La,Ca)9(Mg,Fe)Si7(O,OH,F)28 |
4.75 |
5 |
rhom., res. black |
| Monazite-La* |
(La,Ce,Nd,Th,etc.)PO4 |
5.20 |
5 - 5.5 |
mon., waxy/vit. yellow-brown |
*Varieties of these minerals that are particularly rich in lanthanum.
| Chief ore: |
monazite, bastnäsite |
| World production: |
12500 tonnes/year |
| Main mining areas: |
USA, Brazil, India, Sri Lanka, Australia |
| Reserves: |
c. 6 x 109 tonnes |
| Specimen: |
available as chips, ingots or powder. Care! |
| Abundances |
|
| Sun: |
13.5 (relative to H = 1 x 1023) |
| Earth's crust: |
32 p.p.m. |
| Seawater: |
|
| Atlantic surface: |
1.8 x 10-6 p.p.m. |
| Atlantic deep: |
3.8 x 10-6 p.p.m. |
| Pacific surface: |
2.6 x 10-6 p.p.m. |
| Pacific deep: |
6.9 x 10-6 p.p.m. |
| Residence time: |
200 years |
| Classification: |
recycled |
| Oxidation state: |
III |
Other sizes and specifications on request
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