Atoms and Nuclei
Unit 8. Covers Atomic models; Nucleus; Mass-energy and binding energy; Nuclear fission and fusion.
About this unit
This unit looks inside the atom. It begins with the alpha-particle scattering experiment, which led Rutherford to the nuclear model of the atom, and then Bohr's model, which explains the stability of the hydrogen atom and its line spectrum. The second half studies the nucleus itself: its composition, size and density, isotopes, isobars and isotones, and the nuclear force. Mass–energy equivalence leads to mass defect and binding energy, and the binding energy curve explains why both nuclear fission of heavy nuclei and fusion of light nuclei release large amounts of energy.
How to prepare
Memorise Bohr's postulates and the formulas rₙ = n²a₀, Eₙ = –13.6/n² eV and the spectral series with their final levels. Learn R = R₀A^(1/3), 1 u = 931.5 MeV and the shape of the binding-energy curve. Practise numericals on transition energies, wavelengths, nuclear radius ratios, mass defect and energy released in reactions. Learn the parts of a nuclear reactor and the meaning of critical chain reaction.
Topics in this chapter
Atomic models
Alpha-particle scattering, Rutherford and Bohr models and hydrogen spectra.
5 questionsNucleus
Composition, size, isotopes, isobars, isotones and nuclear force.
5 questionsMass-energy and binding energy
Mass defect and binding energy per nucleon.
5 questionsNuclear fission and fusion
Energy from the nucleus.
5 questions