Column Descriptions Relative Isotopic Standard Isotope Atomic Mass Composition Atomic Weight Notes _________________________________________________________________________ 54 Xe 124 123.9058920(19) 0.000952(3) 131.293(6) g,m 126 125.9042983(38) 0.000890(2) 128 127.9035310(11) 0.019102(8) 129 128.9047808611(60) 0.264006(82) 130 129.903509349(10) 0.040710(13) 131 130.90508406(24) 0.212324(30) 132 131.9041550856(56) 0.269086(33) 134 133.90539466(90) 0.104357(21) 136 135.907214484(11) 0.088573(44) _________________________________________________________________________NIST | Physical Measurement Laboratory | Physical Reference Data | Atomic Weights and Isotopic Compositions Main Page