Column Descriptions Relative Isotopic Standard Isotope Atomic Mass Composition Atomic Weight Notes _________________________________________________________________________ 76 Os 184 183.9524885(14) 0.0002(1) 190.23(3) g 186 185.9538350(16) 0.0159(3) 187 186.9557474(16) 0.0196(2) 188 187.9558352(16) 0.1324(8) 189 188.9581442(17) 0.1615(5) 190 189.9584437(17) 0.2626(2) 192 191.9614770(29) 0.4078(19) _________________________________________________________________________NIST | Physical Measurement Laboratory | Physical Reference Data | Atomic Weights and Isotopic Compositions Main Page