Introduction to Modern Physics: Nuclear Physics and Elementary Particles

Introduction

In the comics, the Incredible Hulk was transformed by exposure to high levels of gamma radiation. As awesome as it might be to have the physical strength of the Hulk, such gamma ray exposure would most likely kill any living thing exposed to the radiation. The nuclear processes that create radiation are fairly well understood in the scientific world if not in the world at large. This unit will take you up close and personal with the nuclei of atoms as you discover some of their more intimate process. These will include radioactive decay, nuclear fission, and nuclear fusion.

Essential Questions

What is radioactive decay?
How does the structure of the nucleus determine if it is stable?
What is the difference between large stable nuclei and large unstable nuclei?
What are the byproducts of radioactive decay?
How does the half-life of a substance describe its radioactive decay?
How do the processes of nuclear fission and fusion change the properties of an atom?

Key Terms

proton - A subatomic nucleon particle with positive charge.
neutron - A subatomic nucleon particle with neutral charge.
strong nuclear force - The force that holds protons together in the nucleus against their electromagnetic repulsion.
weak nuclear force - The force responsible for allowing subatomic particles, like quarks, to change during radioactive decay.
alpha decay - The emission of an alpha particle (helium nucleus) from the nucleus of an atom.
beta decay - The conversion of a neutron into a proton and electron where the proton remains in the nucleus and the electron is ejected.
gamma decay - The production of a high-energy photon by a nucleus in an excited state.
half-life - The time it takes for half of a sample to undergo radioactive decay.
Nuclear fission - The process of splitting a larger atom into smaller atoms.
Nuclear fusion - The process of building larger nuclei by combining smaller nuclei.

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