Column Descriptions

                                                                         
             Relative           Isotopic      Standard                   
Isotope      Atomic Mass        Composition   Atomic Weight    Notes     
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19  K   39   38.9637064864(49)  0.932581(44)  39.0983(1)        
        40   39.963998166(60)   0.000117(1) 
        41   40.9618252579(41)  0.067302(44)
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