💏intro to chemistry review

Alpha particles (α particles)

Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025

Definition

Alpha particles (α particles) are helium nuclei consisting of two protons and two neutrons. They are emitted during certain types of radioactive decay, such as alpha decay.

5 Must Know Facts For Your Next Test

  1. Alpha particles have a +2 charge due to the presence of two protons.
  2. They have relatively low penetration power and can be stopped by a sheet of paper or human skin.
  3. Alpha particles were crucial in Rutherford's gold foil experiment that led to the discovery of the atomic nucleus.
  4. Because they are heavy and carry a double positive charge, alpha particles ionize other atoms strongly along their path.
  5. In nuclear equations, alpha emission is often represented as either α or $^4_2He$.

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