Column Descriptions Relative Isotopic Standard Isotope Atomic Mass Composition Atomic Weight Notes _________________________________________________________________________ 92 U 233 233.0396355(29) 238.02891(3) g,m 234 234.0409523(19) 0.000054(5) 235 235.0439301(19) 0.007204(6) 236 236.0455682(19) 238 238.0507884(20) 0.992742(10) _________________________________________________________________________NIST | Physical Measurement Laboratory | Physical Reference Data | Atomic Weights and Isotopic Compositions Main Page