MASS DEFECT AND BINDING ENERGY DOE-HDBK-1019/1-93 Atomic and Nuclear Physics Example: Calculate the mass defect for lithium-7.   The mass of lithium-7 is 7.016003 amu. Solution: D m   Z m_p        m_e    A      Z   m_n    m_atom D m   3 1.007826  amu    7      3   1.008665  amu       7.016003  amu D m     0.0421335  amu Binding  Energy The loss in mass, or mass defect, is due to the conversion of mass to binding energy when the nucleus is formed.   Binding energy is defined as the amount of energy that must be supplied to a nucleus to completely separate its nuclear particles (nucleons).    It can also be understood as the  amount  of  energy  that  would  be  released  if  the  nucleus  was  formed  from  the  separate particles.   Binding energy is the energy equivalent of the mass defect.    Since the mass defect was converted to binding energy (BE) when the nucleus was formed, it is possible to calculate the  binding  energy  using  a  conversion  factor  derived  by  the  mass-energy  relationship  from Einstein's Theory of Relativity. Einstein's famous equation relating mass and energy is E = mc² where c is the velocity of light (c = 2.998 x 10⁸ m/sec). The energy equivalent of 1 amu can be determined by inserting this quantity of mass into Einstein's equation and applying conversion factors.          E      m  c² 1  amu                               1.6606  x  10 ²⁷kg 1  amu 2.998  x  10⁸ m sec 2 1  N 1          kg  m sec²             1  J 1  N  m 1.4924  x  10 ¹⁰J                            1  MeV 1.6022  x  10 ¹³J 931.5  MeV Conversion Factors: 1 amu =   1.6606 x 10 ^-27 kg 1 newton =   1 kg-m/sec² 1 joule =   1 newton-meter 1 MeV =   1.6022 x 10^-13 joules NP-01 Page 18 Rev. 0