• Atomic Mass: 138.9055 amu
• Atomic weight: 138.90547 (7) g
• Atomic number: 57
• Number of Neutrons (most common/stable nuclide): 82

Physical Properties

• Description:Soft silvery white transition metal that rapidly tarnishes in air. It will burn easily if ignited.

• Atomic Mass Average: 138.9055
• Boiling Point: 3730K 3457°C 6255°F
• Coefficient of lineal thermal expansion/K-1: 4.9E-6
• ConductivityElectrical: 0.0126 106/cm
  Thermal: 0.135 W/cmK
• Density: 6.15g/cc @ 300K
• Elastic Modulus:
  • Bulk: 28/GPa
  • Rigidity: 14.9/GPa
  • Youngs: 37.9/GPa
• Enthalpy of Atomization: 431 kJ/mole @ 25°C
• Enthalpy of Fusion: 6.2 kJ/mole
• Enthalpy of Vaporization: 399.6 kJ/mole
• Flammablity Class:
• Freezing Point: see melting point
• Hardness Scale
  • Brinell: 363 MN m-2
  • Mohs: 2.5
  • Vickers: 491 MN m-2
• Heat of Vaporization: 414kJ/mol
• Melting Point: 1193K 920°C 1688°F
  
• Molar Volume: 22.6 cm3/mole
• Physical State (at 20°C & 1atm): Solid
• Specific Heat: 0.19J/gK
• Vapor Pressure = 1.33E-07Pa@920°C

Chemical Properties

• Electrochemical Equivalent: 1.7275g/amp-hr
• Electron Work Function: 3.5eV
• Electronegativity: 1.1 (Pauling); 1.08 (Allrod Rochow)
• Heat of Fusion: 6.2kJ/mol
• Incompatibilities:
  
• Ionization Potential
  • First: 5.58
  • Second: 11.059
  • Third: 19.174
• Valance Electron Potential (-eV): 40.71
• 
  
• 

• Levels In Humans:
  
  • Blood/mg dm-3: n/a
  • Bone/p.p.m: <0.08
  • Liver/p.p.m: 0.3
  • Muscle/p.p.m: 0.0004
  • Daily Dietary Intake: n/a
  • Total Mass In Avg. 70kg human: 0.8 mg
  
  
• Abundance:
• Found with rare earths in monazite and bastnasite. Around 12,500 tons are produced world wide each year. Primary mining areas are USA, Brazil, India, Sri Lanka, Australia.
• Earth's Crust/p.p.m.: 32
• Seawater/p.p.m.:
  • Atlantic Suface: 0.0000018
  • Atlantic Deep: 0.0000038
  • Pacific Surface: 0.0000026
  • Pacific Deep: 0.0000069
• Atmosphere/p.p.m.: N/A

• Carbon lighting applications, especially by the motion picture industry for studio lighting and projection.
• La2O3 improves the alkali resistance of glass, and is used in making special optical glasses, such as:
  • Infrared absorbing glass.
  • Camera and telescope lenses, because of the high refractive index and low dispersion of rare-earth glasses.
• Small amounts of lanthanum added to steel improves its malleability, resistance to impact and ductility.
• Small amounts of lanthanum added to iron helps to produce nodular cast iron.
• Small amounts of lanthanum added to molybdenum decreases the hardness of this metal and its sensitivity to temperature variations.
• Mischmetal, a pyrophoric alloy used e.g. in lighter flints, contains 25% to 45% lanthanum.
• Lanthanum oxide and the boride are used in electronic vacuum tubes as hot cathode materials with strong emissivity of electrons. Crystals of LaB6 are used in high brightness, extended life, thermionic electron emission sources for scanning electron microscopes.
• in Gas tungsten arc welding electrodes, as a substitute for radioactive thorium.
• Hydrogen sponge alloys can contain lanthanum. These alloys are capable of storing up to 400 times their own volume of hydrogen gas in a reversible adsorption process.
• Petroleum cracking catalysts.
• Gas lantern mantles.
• Glass and lapidary polishing compound.
• La-Ba age dating of rocks and ores.
• Lanthanum carbonate is used medically as a phosphate binder for the treatment of hyperphosphatemia.
  
• Lanthanum nitrate is mainly applied in specialty glass, water treatment and catalyst.
• Cerium activated Lanthanum bromide is the recent inorganic scintillator which has a combination of high light yield and the best energy resolution.