Atomic Weights and Isotopic Compositions for Lanthanum
 Isotope   Relative
Atomic Mass 		    Isotopic
  Composition  		 Standard
Atomic Weight 		  Notes 
 
57 La 138 137.907 1149(37)   0.000 8881(71)  138.905 47(7) g
139 138.906 3563(24)   0.999 1119(71)

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