radiation

• Alpha Decay


  Decreases the charge and the mass of the nucleus
• Alpha Decay


  1. Nucleus emits an alpha particle

  2. Nucleus has 2 less protons and 2 less neutrons

  3. Atomic number decreases by 2

  4. Mass number decreases by 4
• Beta Minus Decay


  A neutron changes into a proton and an electron is emitted
• Beta Minus Decay


  1. Atomic number increases by 1

  2. Mass number stays the same
• Positron Emission


  Decreases the charge of the nucleus
• Positron Emission


  1. A proton changes into a neutron and a positron is emitted

  2. Atomic number decreases by 1

  3. Mass number stays the same
• Neutron Emission


  Decreases the mass of the nucleus
• Neutron Emission


  1. Nucleus emits a neutron

  2. Atomic number stays the same

  3. Mass number decreases by 1
• Beta particles


  • Can be electrons or positrons
  • A beta minus particle is a simply a fast moving electron released by the nuclens
  • beta minus particles have virtual no mass and a relative charge of -1
  • a beta plus particle is a fast moving positron
  • It has exactly the same mass of an electron but a +1 charge
  • They are both moderately ionising
  • beta minus particles are absorbed by a sheet of aluminium (around 5mm thick)
  • Positrons have a smaller range because when they hit an electron the two destroy each other and produce gamma rays
  • this is called annihilation and its used in Medical imaging
• Gamma Particle


  • They are electromagnetic waves with a short wavelength
  • After a nucleus has decayed, It goes through Nuclear rearrangement
  • They penetrate Far Into Materials without being Stopped
  • travel a long distance
  • This means they are weakly ionising because they tend to pass through rather than collide with atoms
  • eventually they hit something and do damage
  • can be absorbed by thick Sheets of lead of metres of contacte
• Alpha particles


  Helium nuclei
• Alpha radiation


  Alpha particle (a) is emitted from the nucleus
• Alpha particle


  • Consists of two neutrons and two protons like a helium nucleus
• Alpha particles


  • Don't penetrate very far into materials
  • Are stopped quickly
• Alpha particles


  • Can only travel a few cm in air
  • Are absorbed by a sheet of paper
• Alpha particles


  • Are strongly ionising due to their size