Mass Difference and Binding Energy

• What is the total mass of a nucleus compared to the sum of its nucleons?

  It is less than the sum
• What is the term for the difference in mass of a nucleus?

  Mass defect
• How is mass defect defined?

  Difference between atom's mass and nucleons' mass

  
• How can the mass defect Δm of a nucleus be calculated?

  Δm = Zm + (A – Z)m - m
• What does Z represent in the mass defect equation?

  Proton number
• What does A represent in the mass defect equation?

  Nucleon number
• What is the mass of a proton denoted as in the mass defect equation?

  m_p
• What is the mass of a neutron denoted as in the mass defect equation?

  m_n
• What is the measured mass of the nucleus denoted as in the mass defect equation?

  m_total
• What happens to the mass of separated nucleons compared to bound nucleons?

  Separated nucleons have greater mass
• What does the decrease in mass imply about energy?

  Energy is released in the process
• What is binding energy?

  Energy required to separate nucleons

  
• How is the total energy of a nucleus related to its constituent nucleons?

  It is less than the sum of their energies
• What type of reaction is the formation of a nucleus?

  Exothermic reaction
• How can the binding energy be calculated?

  E = Δmc

  
• In what units are binding energies typically measured?

  MeV

  
• How does the binding energy of nuclei compare to that of electrons in atoms?

  Nuclear binding energy is much larger

  
• What distinguishes nuclear reactions from chemical reactions?

  Nuclear reactions involve nuclear binding energy changes
• What is the nuclear mass of potassium-40?

  39.953 548 u
• What is the mass of one neutron?

  1.008 665 u
• What is the mass of one proton?

  1.007 276 u
• How do you calculate the number of neutrons in potassium-40?

  N = 40 - 19
• What is the mass defect Δm for potassium-40?

  Δm = 0.36666 u
• How do you convert mass defect from u to kg?

  Δm = 0.36666 × (1.661 × 10⁻²⁷)
• What is the speed of light denoted as in the mass-energy equivalence equation?


  c
• What is the binding energy E for potassium-40?

  E = 5.5 × 10⁻¹³ J
• How do you determine the binding energy per nucleon?

  Divide binding energy by number of nucleons

  
• What is the conversion factor from J to MeV?

  1 MeV = 1.6 × 10⁻¹³ J
• What is the unified atomic mass unit (u) roughly equal to?

  Mass of one proton or neutron

  
• What is the value of 1 u in kg?

  1.66 × 10⁻²⁷ kg
• How is the a.m.u defined?

  Mass of one-twelfth of carbon-12 atom
• What is the mass of one atom of carbon-12?

  Exactly 12 u
• How can the a.m.u be expressed in MeV?

  1 u is equivalent to 931.5 MeV
• How is the mass of an atom in a.m.u related to its nucleon number?

  It is roughly equal to the sum of nucleons
• When should the term mass defect be used?

  When all nucleons are separated
• How can the mass of the nucleus of copernicium-285 be estimated?

  By calculating based on nucleon numbers