Column Descriptions Relative Isotopic Standard Isotope Atomic Mass Composition Atomic Weight Notes _________________________________________________________________________ 56 Ba 130 129.9063207(28) 0.00106(1) 137.327(7) 132 131.9050611(11) 0.00101(1) 134 133.90450818(30) 0.02417(18) 135 134.90568838(29) 0.06592(12) 136 135.90457573(29) 0.07854(24) 137 136.90582714(30) 0.11232(24) 138 137.90524700(31) 0.71698(42) _________________________________________________________________________NIST | Physical Measurement Laboratory | Physical Reference Data | Atomic Weights and Isotopic Compositions Main Page