Column Descriptions Relative Isotopic Standard Isotope Atomic Mass Composition Atomic Weight Notes _________________________________________________________________________ 10 Ne 20 19.9924401762(17) 0.9048(3) 20.1797(6) g,m 21 20.993846685(41) 0.0027(1) 22 21.991385114(18) 0.0925(3) _________________________________________________________________________NIST | Physical Measurement Laboratory | Physical Reference Data | Atomic Weights and Isotopic Compositions Main Page