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Chapter 20: Radioactivity and Nuclear Physics

Difficulty Level: At Grade Created by: CK-12
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The Big Idea

The nuclei of atoms are affected by three forces: the strong nuclear force, which causes protons and neutrons to bind together, the electric force, which is manifested by repulsion of the protons and tends to rip the nucleus apart, and the weak nuclear force, which causes neutrons to change into protons and vice versa.

The strong force predominates and can cause nuclei of complex atoms with many protons to be stable. The electric force of repulsion is responsible for fission, the breaking apart of nuclei, and therefore also for atom bombs and nuclear power. A form of fission where a helium nucleus is a product, is called alpha radiation. The actions of the weak force give rise to beta radiation. A change in nuclear energy can also give rise to gamma radiation, high energy electromagnetic waves. Particles that emit alpha radiation, beta radiation, and gamma radiation go through the process of radioactive decay, which causes the heating of the molten core of the earth, and has even played a role in the mutations in our evolutionary history. Fission and fusion, the latter occurring when light nuclei combine to form new elements, are accompanied by copious amounts of gamma radiation. These processes often produce radioactive nuclei; in nature these radioactive nuclei were forged in the explosive deaths of ancient stars.

Chapter Outline

Chapter Summary


In these lessons students will develop a deep understanding of radiation and how to solve problems involving the half life and decay constant equations. In addition, the lesson on carbon dating covers an understanding and also develops the skills to solve carbon dating problems.

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Difficulty Level:
At Grade
Date Created:
Aug 17, 2016
Last Modified:
Jan 11, 2017
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