## Chapter Objectives and Summaries

### CHAPTER 29 Quantum Physics and Fundamental particles

LEARNING OBJECTIVES
Knowledge of subject matter
• Recall the Planck-Bohr modification to the Rutherford atom as the quantum model.
• State the basic postulates of the Bohr model of the hydrogen atom.
• Recall that photon quanta have energy given by E=hv, where (h) is the Planck constant having a value of 6.63 x 10-34 Js.
• Define the terms photoelectric effect, work function, threshold energy and stopping potential.
• Perform simple calculations using Compton collision theory, with photon momentum given by (p=h/ÿ).
• Relate the formation of spectra to photon emission due to electron transitions between quantum orbitals.
• State the formula for the Balmer series of spectral lines of the hydrogen atom as (****).
• Recognise a quantum energy level diagram.
• Relate the Franck Hertz experiment to historical verification of quantised energy absorption by atoms.
• Calculate a de Broglie wavelength for a matter wave (h/mv) and recognise the wave particle duality concept.
• Recall the uncertainty principle given by (*** )
• State that the fundamental particles of physics may be classified into hadrons, leptons and bosons and define their characteristics.
• Relate the fundamental forces of physics to fundamental particles through the standard model.
• Identify the basic characteristics of the quark model for hadrons.
• Recall historical sequence of events leading to the ideas of modern relativistic quantum mechanics and cosmology.

Scientific Processes.

• Predict the effect on the Ek(max) verses frequency (f) graph, of variations in photoelectric material or intensity of incident radiation.
• Use the quantum model to explain and interpret line emission spectra of various materials.
• Use tabulated data, or atomic energy level diagrams to predict emitted photon energies, frequencies and wavelengths.
• Write a report on the historical significance of scientific discoveries by quantum physicists.
• Classify fundamental particles on the basis of mass, charge, spin or force interaction.
• Contribute to discussion on the significance of quantum mechanical ideas to our understanding of nature.
• Sketch models of atomic structure and fundamental particle interactions.

Complex reasoning Processes.

• Solve challenging problems using the formulae of photoelectric effect, photon quanta, Compton collisions, spectral emission, matter waves and the uncertainty principle.
• Devise and design simple diagrammatic models to represent the properties of atomic structure.
• Discuss and debate the need for fundamental particle research and its inherent advantages but tremendous costs to society.
• Demonstrate creative thinking in dealing with issues at the forefront of our understanding of the universe.

CHAPTER 29 SUMMARY

• Max Planck postulated the quantum nature of energy absorbed and released by atoms.
• Electromagnetic energy quanta are called photons and possess energy directly related to their frequency E = h f.
• The photoelectric effect is the emission of electrons by metals illuminated by light. It's correct interpretation, in terms of quantum theory was described by Albert Einstein.
• Einstein's interpretation of the photoelectric effect is an extension of the law of conservation of energy.
• Photons and electrons may interact by Compton scattering, with the photon being considered to have particle momentum.
• The wave-particle duality property of matter is an important explanatory tool in quantum mechanics.
• Atomic emission spectra of simple atoms can be mathematically described by applying the quantum theory to atomic structure in what is called the Bohr model of the atom.
• The excitation energy states of any atom can be illustrated with a quantum energy level diagram.
• The Heisenberg uncertainty principle places a physical limit on the ability of experimenters to measure simultaneously, the position and the momentum of any sub atomic particle.
• Modern quantum mechanical theorists place great importance on the standard model which describes the fundamental force interactions and particles of nature.
• All matter is entirely composed from 6 lepton and 6 hadron particles.
• One of the problems facing modern quantum gravity theories is to provide a comprehensive 'Theory of everything' or TOE which will effectively reduce the standard model to a single theoretical explanation of where the universe has been and where it is going ! Return to Objectives-Summary Menu Page page.