Column Descriptions Relative Isotopic Standard Isotope Atomic Mass Composition Atomic Weight Notes _________________________________________________________________________ 29 Cu 63 62.92959772(56) 0.6915(15) 63.546(3) r 65 64.92778970(71) 0.3085(15) _________________________________________________________________________NIST | Physical Measurement Laboratory | Physical Reference Data | Atomic Weights and Isotopic Compositions Main Page