Difference between revisions of "Lanthanum"
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| − | '''Lanthanum''' is a rare-earth metal with chemical symbol '''La''', and an atomic weight of 57. Lanthanum is the first element in the [[lanthanide]] series. | + | '''Lanthanum''' is a rare-earth metal with chemical symbol '''La''', and an atomic weight of 57. Lanthanum is the first element in the [[lanthanide]] element series. |
Lanthanum's position in the [[periodic table]] is shown different depending on the type of table. Some models put it in group 3, others or at the end of the f block with [[lutetium]] and lawrencium instead, while other types of tables only have [[scandium]] and [[yttrium]], leaving lanthanum in the f block. | Lanthanum's position in the [[periodic table]] is shown different depending on the type of table. Some models put it in group 3, others or at the end of the f block with [[lutetium]] and lawrencium instead, while other types of tables only have [[scandium]] and [[yttrium]], leaving lanthanum in the f block. | ||
Revision as of 03:56, 11 April 2019
| General properties | |||||
|---|---|---|---|---|---|
| Name, symbol | Lanthanum, La | ||||
| Appearance | Silvery-white | ||||
| Lanthanum in the periodic table | |||||
| |||||
| Atomic number | 57 | ||||
| Standard atomic weight (Ar) | 138.90547(7) | ||||
| Group, block | , d-block | ||||
| Period | period 6 | ||||
| Electron configuration | [Xe] 5d1 6s2 | ||||
| Physical properties | |||||
| Silvery-white | |||||
| Phase | Solid | ||||
| Melting point | 1193 K (920 °C, 1688 °F) | ||||
| Boiling point | 3737 K (3464 °C, 6267 °F) | ||||
| Density near r.t. | 6.162 g/cm3 | ||||
| when liquid, at | 5.94 g/cm3 | ||||
| Heat of fusion | 6.20 kJ/mol | ||||
| Heat of | 400 kJ/mol | ||||
| Molar heat capacity | 27.11 J/(mol·K) | ||||
| pressure | |||||
| Atomic properties | |||||
| Oxidation states | 3, 2, 1 (a strongly basic oxide) | ||||
| Electronegativity | Pauling scale: 1.10 | ||||
| energies |
1st: 538.1 kJ/mol 2nd: 1067 kJ/mol 3rd: 1850.3 kJ/mol | ||||
| Atomic radius | empirical: 187 pm | ||||
| Covalent radius | 207±8 pm | ||||
| Miscellanea | |||||
| Crystal structure | Double hexagonal close-packed (dhcp) | ||||
| Speed of sound thin rod | 2475 m/s (at 20 °C) | ||||
| Thermal expansion | 12.1 µm/(m·K) (α, poly) | ||||
| Thermal conductivity | 13.4 W/(m·K) | ||||
| Electrical resistivity | 6.15·10-7 Ω·m (α, poly) | ||||
| Magnetic ordering | Paramagnetic | ||||
| Young's modulus | 36.6 GPa (α, poly) | ||||
| Shear modulus | 14.3 GPa (α, poly) | ||||
| Bulk modulus | 27.9 GPa (α, poly) | ||||
| Poisson ratio | 0.28 (α, poly) | ||||
| Mohs hardness | 2.5 | ||||
| Vickers hardness | 360–1750 MPa | ||||
| Brinell hardness | 350–400 MPa | ||||
| CAS Registry Number | 7439-91-0 | ||||
| History | |||||
| Discovery | Carl Gustaf Mosander (1838) | ||||
Lanthanum is a rare-earth metal with chemical symbol La, and an atomic weight of 57. Lanthanum is the first element in the lanthanide element series.
Lanthanum's position in the periodic table is shown different depending on the type of table. Some models put it in group 3, others or at the end of the f block with lutetium and lawrencium instead, while other types of tables only have scandium and yttrium, leaving lanthanum in the f block.
Contents
Properties
Chemical
Lanthanum is one of the more reactive rare earth metals. It reacts slowly with cold water, and very quickly with hot water. It will also react with elemental halogens, chalcogens, as well as carbon, phosphorus, nitrogen, silicon, and boron.
Physical
Lanthanum is a silvery white metal that tarnishes quickly in contact with air. It is a very soft metal and can be cut with a knife.
Availability
Lanthanum is readily available from source such as Metallium and eBay.
Preparation
It is difficult to prepare lanthanum metal in an amateur setting, though a method for making rare earth metals, involving reducing the fluoride with calcium metal, is being developed by the Sciencemadness community.
Projects
- Make Mischmetal
- Nickel-metal hydride battery
Handling
Safety
Lanthanum metal will react with water to produce hydrogen, which is flammable. Lanthanum compounds are thought to be non-toxic, however not much research has been done on the toxicity so they should be handled with care.
Storage
Best stored under inert atmosphere.
Disposal
Best to try to recycle it.
