Column Descriptions Relative Isotopic Standard Isotope Atomic Mass Composition Atomic Weight Notes _________________________________________________________________________ 40 Zr 90 89.9046977(20) 0.5145(40) 91.224(2) g 91 90.9056396(20) 0.1122(5) 92 91.9050347(20) 0.1715(8) 94 93.9063108(20) 0.1738(28) 96 95.9082714(21) 0.0280(9) _________________________________________________________________________NIST | Physical Measurement Laboratory | Physical Reference Data | Atomic Weights and Isotopic Compositions Main Page