; Ehleringer, James R; Pataki, Diane E | The isotopic composition of the element can vary in commercial materials, which can cause the atomic weight to deviate significantly from the given value |
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04 6 C 14 2 12! 13 60 Nd 6 144 | 28 - 95 Am 7 243! 9 76 Os 8 6 190 |
36 22 Ti 4 4 048! Nature's Building Blocks: An A-Z Guide to the Elements New ed.
However, three elements, thorium, protactinium, and uranium, have a characteristic terrestrial isotopic composition, and thus their standard atomic weights are given | 094 - 87 Fr 1 7 223! 647 1 21 Sc 3 4 045! 3 - 100 Fm 7 257! Journal of Polymer Science: Polymer Letters Edition |
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The isotopic composition varies in terrestrial material such that a more precise atomic weight can not be given | Ihde, The Development of Modern Chemistry, New York 1964 |
[262] 39 - - - - 106 Sg 6 7 266! 16 43 Tc 7 5 098! 01 33 As 15 4 075! "Absorption Spectrum of N2 in the Extreme Ultraviolet".