Binding Energy and Nuclear Stability

• All nuclei have a mass that is less than the sum of its parts.

• Mass defect: the difference between the theoretical mass (sum of the protons and neutrons) and the actual mass

• Binding energy: the energy that’s produced as a result of the formation of a nucleus FROM the mass loss.

  • The greater the binding energy, the more stable the nucleus.

Radiation

• Unstable nuclei emit radiation.

• The type of radiation is determined by the reason for the instability.

  1. Too many protons.  No stable nucleus has more than 83 protons.

  2. Too many neutrons per proton.

     1. For each number of protons there is an optimum number of neutrons.

     2. Nuclei that stray too far from that number are unstable.

  3. Too few neutrons for that number of protons. (rare)