Unit VIII: Atomic and Nuclear Physics

Introduction

When people think of nuclear physics they commonly think of nuclear reactors. What we will be studying is the radioactivity of minerals in the earth’s core, which power geysers, natural hot springs, and volcanoes. This unit should take about two weeks to teach. It should be divided into three sections, the atom and the quantum, atomic nucleus and radioactivity, and nuclear fission and fusion. Intended Learning Outcomes
 
General Instructional Objectives (and corresponding Specific Learning Outcomes) Unit Content
Knows terms

Understands the meaning of terms

atomic nucleus, atomic number, atomic mass number, bohr model, quantized energy levels, x-, alpha, beta, and gamma rays, alpha and beta particles, nucleon, quarks, isotopes, half-life, nuclear fission and fusion, thermonuclear fusion, critical mass
Understands scientific concepts Ritz combination principle, de Broglie matter waves, quantum mechanics, Schrodinger’s wave equation, chain reaction, Correspondence principle, transmutation
Knows all laboratory procedures

Prepares a plan for an experiment

Participates in classroom activities

Respects the scientific process

Displays a scientific attitude

Demonstrates skills in laboratory work

All content

 

Instructional Foci

Homework, quizzes, class discussion, questions for thought from the Flying Circus of Physics Teaching Strategies The Bohr model of the atom should be introduced. Also atomic spectra, similar to the spectra we observed using our spectroscope, should be studied. Then the relative sizes of atoms as dictated by the electrical force from electrical charge in their nucleus should be discussed. Then the teacher should try to explain quantized energy levels based on the electron acting as a wave—a de Broglie matter wave. Then the study of quantum mechanics should be discussed, including a discussion of Schrodinger’s wave equation.

To begin the section on the atomic nucleus and radioactivity, the teacher should discuss x-rays and radioactivity. Then alpha, beta, and gamma rays should be discussed. Excuse the dry nature, but then the nucleus should be studied in greater depth. The teacher should note that the nucleus is composed of nucleons, which are thought to be made of quarks that have funny names like "truth", "charm", and "beauty", and have never been isolated and experimentally observed. Isotopes are atoms that have the same number of protons, but different a different number of neutrons. The teacher can then discuss why atoms are radioactive and their half-life. When an element emits a beta or an alpha particle a different element is created. This is called a transmutation. Natural transmutations of elements should be discussed. Carbon dating is used to date everything from rocks to ancient skeletons. It is based on radioactive isotopes and their half-lives among other things. Uranium dating is also used, but it is used to date older, nonliving things. It may be useful to discuss the effects of radiation on humans.

In nuclear fission the uranium nucleus divides. Extra neutrons are liberated in the fission process, which, in turn, can cause more fission reactions in a chain reaction. Nuclear reactors and breeder reactors can then be discussed. Plutonium, which was the element in the atomic bomb, can be explored. Einstein’s mass energy equivalence, E = mc2, can be introduced by talking about the slightly complicated, yet pervasive throughout science laboratories, the mass spectrometer. Then the teacher can discuss fusing hydrogen isotopes together to form helium nuclei in a nuclear fusion reaction. Nuclear fusion is thought to hold the key to the future of recycling using a fusion torch, creating electrical power, and desalinating water.
 

Special Notes
1. Quantum physics is completely conceptual, which is good. However, it has few, if any, examples in the real world. The teacher must rely on clear lectures and lengthy discussion to achieve optimal understanding by the students.
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