GCSE Physics (AQA)

346 videos | 23 hours

Alpha Decay Equations

Please subscribe to watch this video.

This, and all other videos, are included in our premium subscriptions.

Premium accounts get access to all videos.

Atomic structure Atoms and nuclear radiation

Alpha Decay Equations

3:09 Decay Equations
Spec 4.4.2.2
Previous Discovery of Protons & Neutrons Next Beta Decay Equations
  • Alpha decay involves a nucleus losing two protons and two neutrons.
  • Nuclei that undergo alpha decay are typically too large to remain stable.
  • The emitted alpha particle consists of two protons and two neutrons bound together.
  • Post-decay, the nucleus becomes smaller and more stable due to its reduced size.
  • The mass number of the nucleus decreases by four and the atomic number decreases by two after alpha decay.
  • Atomic notation includes the mass number (A) representing total neutrons and protons, and the atomic number (Z) representing just the protons.
  • The element symbol (X) identifies the element.
  • A nuclear equation for alpha decay can be written, showing changes in A and Z, similar to a chemical equation.
  • The alpha particle is represented as a helium nucleus in the equation.
  • The new nucleus (Y) is a different element due to the change in proton number.
  • The new mass number is calculated by subtracting four from the original, and the new atomic number by subtracting two.
  • The equation's correctness is verified by ensuring the total A and Z values are consistent on both sides.
  • The new atomic number helps identify the new element resulting from the decay.
  • The new nucleus may undergo further decays to reach stability.
  • Example given: Polonium-210 (Po) with 84 protons and 126 neutrons undergoes alpha decay to become Lead-206 (Pb) with 82 protons.
  • Steps to write the nuclear equation include adjusting the atomic and mass numbers and identifying the resulting element.

Please subscribe to access these revision notes.

This, and all other video notes, are included in our premium subscriptions.

Premium accounts get access to all videos and revision notes.