Lanthanum is a soft, ductile, silvery-white rare-earth metal element with symbol La and atomic number 57. In the periodic table, it is the first element of the lanthanide series. It oxidizes rapidly when exposed to air. Lanthanum compounds have numerous applications as catalysts, additives in glass, carbon lighting for studio lighting and projection, ignition elements in lighters and torches, electron cathodes, scintillators, GTAW electrodes, and others. Lanthanum carbonate (La2(CO3)3) has been approved as a medicine for treating renal failure.