Column Descriptions

                                                                         
             Relative           Isotopic      Standard                   
Isotope      Atomic Mass        Composition   Atomic Weight    Notes     
_________________________________________________________________________
51  Sb  121  120.9038120(30)    0.5721(5)     121.760(1)       g
        123  122.9042132(23)    0.4279(5)   
_________________________________________________________________________

NIST | Physical Measurement Laboratory | Physical Reference Data | Atomic Weights and Isotopic Compositions Main Page