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 !