Atomic Weights and Isotopic Compositions for Tantalum
Column Descriptions

                                                                         
             Relative           Isotopic      Standard                   
Isotope      Atomic Mass        Composition   Atomic Weight    Notes     
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73  Ta  180  179.9474648(24)    0.0001201(32)  180.94788(2)      
        181  180.9479958(20)    0.9998799(32)
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