Obtain the binding energy of the nuclei 5626Fe and 20983Bi in units of MeV from the following data: (a) m(5626Fe)=55.934939u (b) m(20983Bi)=208.980388u
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Solution
(a) 5626Fe contains 26 protons and 30 neutrons.
Mass of 26 protons=26×1.007825u=26.26345u
Mass of 30 neutrons=30×1.008665u=30.25995u
Mass of 5626Fe nucleus=55.934939u
Thus, mass defect Δm=26.26345u+30.25995u−55.934939u=0.528461u.
Thus, binding energy of 5626Fe nucleus is 0.528461×931.5MeV=492.26MeV.
Binding energy per nucleon=492.26MeV56=8.790MeV
(b) 20983Bi contains 83 protons and 126 neutrons.
Mass of 83 protons=83×1.007825u=83.649475u
Mass of 126 neutrons=126×1.008665u=127.09170u
Mass of 20983Bi nucleus=208.986388u
Thus, mass defect Δm=83.649475u+127.09170u−208.986388u=1.760872u.
Thu,s binding energy of 20983Bi nucleus is 1.760872×931.5MeV=1640.26MeV.