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Section: 1 | Atomic Masses and Isotopic Abundances |
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The table 'Atomic Masses and Isotopic Composition of the Elements 2019' has one or more different columns to those in the book version.
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The recommended form of citation is:
John R. Rumble, ed., CRC Handbook of Chemistry and Physics, 103rd Edition (Internet Version 2022), CRC Press/Taylor & Francis, Boca Raton, FL.
If a specific table is cited, use the format: "Physical Constants of Organic Compounds," in CRC Handbook of Chemistry and Physics, 103rd Edition (Internet Version 2022), John R. Rumble, ed., CRC Press/Taylor & Francis, Boca Raton, FL.

ATOMIC MASSES AND ISOTOPIC ABUNDANCES

This table lists the mass (in atomic mass relative to 12C = 12), and the representative abundance (fractional) of the stable nuclides and selected radioactive nuclides. At least one isotope of each of the 118 known elements is included.  The atomic masses were taken from the AME 2016 evaluation of the Atomic Mass Data Center, now located at the Institute of Modern Physics in Lanzhou, China (Refs. 1-3). The number in parentheses following the mass value is the uncertainty in the last digit(s) given. The mass values for the artificially produced elements were derived from a combination of experimental data and systematic trends. Mass values that are estimates, without experimental measurements, are indicated by a footnote. Column definitions for the table are as follows.

Column heading Definition
Z Atomic number of isotope
Isotope Isotope symbol
Mass (relative to 12C = 12 Atomic mass relative to 12C =12
Abundance Representative abundance (fractional) of the isotope
Note Refer to notes at end of table

Natural isotopic abundance values were taken from the IUPAC Report "Isotopic Compositions of the Elements 2019" (Ref. 4); these entries are either a range in square brackets or followed by uncertainties in the last digit(s) of the stated values. This uncertainty includes both the estimated measurement uncertainty and the reported range of variation in different terrestrial sources of the element (see Ref. 5 for full details and caveats regarding elements whose abundance is variable).  The absence of an entry in the Abundance column indicates a radioactive nuclide is not present in nature or an element whose isotopic composition varies so widely that a meaningful natural abundance cannot be defined.

References 1 and 2 contain mass data on over 3000 nuclides and describe the evaluation procedure in detail. Masses and other properties of nuclides may also be found in Section 11, "Table of the Isotopes” (Ref. 6).

References

  1. Huang, W. J., Audi, G., Wang, M., Kondev, F. G., Naimi, S., and Xu, X., Chinese Physics C41, 030002, 2017 [https://doi.org/10.1088/1674-1137/41/3/030002]
  2. Wang, M., Audi, G., Kondev, F. G., Huang, W. J., Naimi, S., and Xu, X., Chinese Physics C41, 030003, 2017 [https://doi.org/10.1088/1674-1137/41/3/030003]
  3. IAEA Nuclear Data Services, <www-nds.iaea.org/amdc/>.
  4. See Isotopic Compositions of the Elements 2019, <www.ciaaw.org>.
  5. Meija, J., et al, Pure Appl. Chem. 88, 293, 2016  [https://doi.org/10.1351/PAC-REP-10-06-02]
  6. Holden, N. E., "Table of the Isotopes," in Rumble, J. R., Ed., CRC Handbook of Chemistry and Physics, 101st Edition., CRC Press, Boca Raton, FL 2020.
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Atomic Masses and Isotopic Composition of the Elements 2019



ElementZIsotopeMass (relative to 12C = 12)AbundanceNotes
Continued on next page...
Hydrogen11H1.00782503224(9)[0.999 72, 0.999 99]m
Hydrogen2H2.01410177811(12)[0.000 01, 0.000 28]m
Hydrogen3H3.01604928199(23)
Helium23He3.01602932265(22)0.000 002(2)g r
Helium4He4.00260325413(6)0.999 998(2)g r
Lithium36Li6.0151228874(15)[0.019, 0.078]m
Lithium7Li7.016003437(5)[0.922, 0.981]m
Beryllium49Be9.01218307(8)1
Boron510B10.012936862(16)[0.189, 0.204]m
Boron11B11.009305167(13)[0.796, 0.811]m
Carbon611C11.01143260(6)
Carbon12C12[0.9884, 0.9904]
Carbon13C13.00335483521(23)[0.0096, 0.0116]
Carbon14C14.003241988(4)
Nitrogen714N14.00307400446(21)[0.995 78, 0.996 63]
Nitrogen15N15.0001088989(6)[0.003 37, 0.004 22]
Oxygen816O15.99491461960(17)[0.997 38, 0.997 76]
Oxygen17O16.9991317566(7)[0.000 367, 0.000 400]
Oxygen18O17.9991596128(8)[0.001 87, 0.002 22]

  • aEstimated value, not based on experimental measurement.
  • gGeological materials are known in which the element has an isotopic composition outside the limts for normal material. The difference between the atomic weight of the element in such materials and that given in the table may exceed the stated uncertainty.
  • mModified isotopic compositions may be found in commercially available material because the material has been subjected to an undisclosed or inadvertent isotopic fractionation. Substantial deviations in atomic weight of the element from that given in the table can occur.
  • rRange in isotopic composition of normal terrestrial material prevents a more precise standard stomic weight being given; the tabulated atomic-weight value an uncertainty should be applicable to normal materials.


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