Section 1 review
We infer the presence of a strong nuclear force because positively charged protons in the nucleus would otherwise repel each other. The strong nuclear force is much stronger than the Coulomb force, but its range does not extend beyond the approximate size of a nucleus. The energy captured in the nucleus is called binding energy and is calculated by Einstein’s equation of mass–energy equivalence. The mass of a nucleus of an element is less than the mass of its constituent nucleons. The difference is called mass deficiency. The mass deficiency and binding energy of a nucleus are related through Einstein’s equation.

For more information to research the historical development of the concepts of the strong (and weak) forces, see
  • Coming of Age in the Milky Way by Timothy Ferris,
  • Strange Beauty by George Johnson, and
  • Story of the W and Z by Peter Watkins.
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strong nuclear force, atomic mass unit (amu), mass–energy equivalence, rest energy, binding energy, mass deficiency

E=m c 2

Review problems and questions

  1. Research and describe the historical development of the concept of the strong nuclear force. Read the text aloud Show
  1. What is the rest energy of an electron (whose mass = 9.11 × 10−31 kg)?
    1. 1.0 × 10−47 J
    2. 3.0 × 10−39 J
    3. 2.7 × 10−22 J
    4. 8.2 × 10−14 J Read the text aloud Show
  1. In your body, are there more protons than neutrons? More protons than electrons? Read the text aloud Show
  1. The isotope O 8 16 has a mass of 15.99491 amu. What is its binding energy? Read the text aloud Show
  1. Calculate the mass deficiency for the nucleus of tritium H 1 3 , which is an isotope of hydrogen with a mass of 3.0160 amu. (The mass of a proton is 1.0073 amu, the mass of a neutron is 1.0087 amu, and the mass of an electron is 0.0005 amu.) Read the text aloud Show
  1. What is the binding energy of the nucleus of a tritium atom? Read the text aloud Show

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