SOME FEATURES OF THE RELATIONSHIP BETWEEN MASS DEFECT AND MASS NUMBER

Abstract

The variation of mass defect with mass number (naturally occurring isotopes only) has been examined using the critically revised mass data of Wapstra (1955). Three principal features may be distinguished; two can be correlated with significant N = 50 and N = 82, and the third, with isotope abundance distribution and variation (Ahrens, 1957). The mass defect vs. A route followed by the odd A isotopes is very clearly defined whereas the spread of points about the even A trend is quite considerable, particularly over the range A = ~60 to A = ~140. This is due to overlapping of trough-like distributions of mass defect for each value of even Z. Each such isotopic distribution approximates roughly to a parabola with one shortened limb.