Relative Atomic Masses and Natural Isotopic Composition of the Elements

Relative Atomic Masses and Natural Isotopic Composition of the Elements 

The Table of Atomic Weights of the Elements 1981 is reprinted below. Added to this list are the relative atomic masses for the electron (e ) and deuterium (D). The relative atomic mass for the electron is given by Cohen and Taylor. 

The 1981 report on atomic weights includes a complete review of the natural isotopic composition of the elements and also tabulates the relative atomic masses for selected radioisotopes. This information is required for the conversion of spectroscopic data from that corresponding to specific isotopes to the naturally occurring isotopic abundance. 

As in the lUPAC report, values in parentheses are used for radioactive elements whose relative masses cannot be quoted exactly without knowledge of the origin of the elements the value given is the atomic mass number of the isotope of that element of longest known half life. Alternatively, the relative atomic mass of the isotope with the longest known half life or that of a commonly used isotope could be listed, since the relative atomic masses of the individual isotopes are accurately known. 

---