Alpha and Beta Decay

• What process do unstable nuclei undergo to become more stable?

  Radioactive decay
• What are the three common decay mechanisms?

  • Alpha decay
  • Beta-minus decay
  • Beta-plus decay

  
• In which type of nuclei is alpha decay common?

  Large, unstable nuclei with too many nucleons
• What does an alpha particle consist of?

  2 protons and 2 neutrons

  
• What happens to a parent nucleus during alpha decay?

  It emits an alpha particle and changes

  
• What is the equivalent of an alpha particle?

  A helium nucleus
• What changes occur in the nucleus during alpha decay?

  Proton number decreases by 2, nucleon number by 4

  
• What is a beta-minus particle?

  A high energy electron emitted from the nucleus

  
• What occurs during beta-minus decay?

  A neutron turns into a proton, emitting an electron

  
• What happens to the proton number during beta-minus decay?

  It increases by 1

  
• What remains unchanged during beta-minus decay?

  The total number of nucleons
• What is a beta-plus particle?

  A high energy positron emitted from the nucleus

  
• What occurs during beta-plus decay?

  A proton turns into a neutron, emitting a positron

  
• What happens to the proton number during beta-plus decay?

  It decreases by 1

  
• What remains unchanged during beta-plus decay?

  The total number of nucleons
• What is an electron neutrino?

  A subatomic particle with no charge
• When are electron anti-neutrinos produced?

  During beta-minus decay

  
• Why was the existence of neutrinos hypothesized?

  To account for conservation of energy in beta decay
• How do alpha particles differ from beta particles in terms of energy levels?

  Alpha particles have discrete energy levels

  
• What does the graph of beta particles against kinetic energy show?

  A curve indicating a continuous range of energies

  
• What is shared between beta particles and neutrinos during beta decay?

  The energy released in the decay

  
• What are the key differences between alpha and beta decay?

  Alpha Decay:

  • Emits an alpha particle (helium nucleus)
  • Proton number decreases by 2
  • Nucleon number decreases by 4

  
  

  Beta-Minus Decay:

  • Emits a beta-minus particle (electron)
  • Proton number increases by 1
  • Nucleon number remains the same

  
  

  Beta-Plus Decay:

  • Emits a beta-plus particle (positron)
  • Proton number decreases by 1
  • Nucleon number remains the same

  
• What is the nucleon number of the radioactive nucleus $^{222}_{86}Rn$ before decay?


  222
• What happens to the nucleon number of Po after alpha decay from $^{222}_{86}Rn$?


  It decreases to 218

  
• What is the proton number of Po after alpha decay from $^{222}_{86}Rn$?


  It decreases to 84

  
• What is the nucleon number of a radioactive substance that decays by beta-plus emission?

  212

  
• What happens to the proton number after beta-plus emission from a nucleus with a proton number of 82?

  It decreases to 80

  
• What happens to the neutron number after beta-plus emission from a nucleus with 130 neutrons?

  It increases to 132

  
• What is the common mistake to avoid regarding neutrons and nucleon number?

  Confusing neutrons with nucleon number
• What is the principle that applies in both alpha and beta emission?

  Conservation of momentum and energy
• How can you remember which particle decays into which in beta emission?

  Think of beta ‘plus’ as ‘proton’ turning into neutron