Lanthanum is a chemical element with the symbol La and atomic number 57. It is a soft, ductile, silvery-white metal that tarnishes slowly when exposed to air and is soft enough to be cut with a knife.
Phase at STP： 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 m.p.)： 5.94 g/cm3
Heat of fusion： 6.20 kJ/mol
Heat of vaporization： 400 kJ/mol
Molar heat capacity： 27.11 J/(mol·K)
Lanthanum compounds have numerous applications as catalysts, additives in glass, carbon arc lamps for studio lights and projectors, ignition elements in lighters and torches, electron cathodes, scintillators, GTAW electrodes, and other things. Lanthanum carbonate is used as a phosphate binder in cases of high levels of phosphate in the blood seen with kidney failure.