12. (a) The mass number Ais the number of nucleons in an atomic nucleus. Since mmpn≈the mass of the nucleus is approximately Amp. Also, the mass of the electrons is negligible since it is much less than that of the nucleus. So MAmp≈. (b) For 1H, the approximate formula gives M ≈Amp= (1)(1.007276 u) = 1.007276 u. The actual mass is (see Table 42-1) 1.007825 u. The percentage deviation committed is then δ= (1.007825 u – 1.007276 u)/1.007825 u = 0.054%
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This note was uploaded on 05/19/2011 for the course PHY 2049 taught by Professor Any during the Spring '08 term at University of Florida.