Chapter 9 – Atoms On Display |
| Activity Summaries |
Physics Principles |
Activity 1: Static Electricity and Coulomb’s Law
Students begin by confronting what they presently know about atoms by commenting on a popular (though flawed) representation of the atom. They then investigate static electricity and Coulomb’s Law to prepare them to understand the forces holding the atom together.
| - Electrostatic forces
- Coulomb’s Law
- Conservation of charge
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Activity 2: Tiny and Indivisible
In a simulation of Millikan’s oil-drop experiment, students use inquiry to find
the number of coins enclosed in a film canister. They then learn how related techniques were used to determine that electric charge is quantized.
| - Charge is quantized
- Millikan oil-drop experiment
- Charge on an Electron
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Activity 3: How Big Is Small?
Using indirect measurements, students are able to accurately determine the size of a penny. They compare their statistical approach with direct measurement. Finally, they compare their experiment with Rutherford’s experiment and are able to recognize the size of the nucleus in relation to the atom and the evidence we have for that knowledge.
| - Indirect measurements
- Size of the nucleus
- Rutherford’s scattering experiment
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Activity 4: Hydrogen Spectra and Bohr’s Model
Students investigate the spectral lines from three gases using a diffraction grating and measure the wavelengths of light. They then learn about the Bohr model of the atom and are able to calculate the wavelengths of light as electrons jump from one orbit to another.
| - Light spectra
- Models of the atom
- Conservation of energy
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Activity 5: Extending and Amending the Model
The wave and particle nature of light is explored by investigations of two-slit interference and the photoelectric effect. Electrons are restricted to a one-dimensional box so that their wave characteristics can be studied. A new interpretation of the Bohr orbits as standing waves of electrons is introduced, with a non-mathematical introduction of the Schrodinger equation.
| - Diffraction of light
- Interference of light
- Wavelength of light
- Photoelectric effect
- Probability functions
- Electron wavelength
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Activity 6: Inside the Nucleus
With a huge Coulomb repulsion pushing protons apart, the need for a strong attractive force in the nucleus is investigated. Students are then introduced to Feynman diagrams as a means of understanding how forces are transmitted.With a huge Coulomb repulsion pushing protons apart, the need for a strong attractive force in the nucleus is investigated. Students are then introduced to Feynman diagrams as a means of understanding how forces are transmitted.
| - Neutrons
- Isotopes
- Nuclear forces
- Feynman diagrams
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Activity 7: Radioactive Decay and the Nucleus
Students investigate the statistical properties of randomly tossing sugar cubes. This is then related to the radioactive decay of nuclei and the use of half-life as a clock. Students then complete nuclear equations for alpha, beta, and gamma decays.
| - Radioactive decay
- Half-life
- Alpha, beta, gamma emission
- Decay series of unranium
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Activity 8: Holding the Nucleus Together
Students calculate the mass defect and binding energies of nuclei by using Einstein’s famous equation E = mc2.
| - E = mc2
- Kinetic energy
- Mass defect
- Binding energy
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Activity 9: Breaking Up Is Hard to Do
After graphing the binding energy per nucleon curve for all of the elements, students explore nuclear fission and fusion. Chain reactions in fission reactions are also studied.
| - Binding energy
- Binding energy per nucleon graph
- Fission
- Fusion
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