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Alpha decay

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College Physics I – Introduction

Definition

Alpha decay is a type of radioactive decay where an unstable nucleus emits an alpha particle, consisting of two protons and two neutrons. This process decreases the atomic number by 2 and the mass number by 4.

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5 Must Know Facts For Your Next Test

  1. An alpha particle is identical to a helium-4 nucleus.
  2. Alpha decay reduces the parent atom's atomic number by 2 and its mass number by 4.
  3. Alpha particles have low penetration power and can be stopped by a sheet of paper or human skin.
  4. Common examples of alpha emitters include radium-226, uranium-238, and plutonium-239.
  5. Alpha decay typically occurs in heavy nuclei where the electrostatic repulsion between protons is very strong.

Review Questions

  • What particles are emitted during alpha decay?
  • How does alpha decay affect the atomic number and mass number of the decaying nucleus?
  • Why do heavy nuclei tend to undergo alpha decay?
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