Radioactivity and Particles

• Radioactive atoms have a certain number of protons and neutrons
• Radioactive decay results in a different number of protons and neutrons
• Isotope


  Atoms with the same number of protons but a different number of neutrons
• Types of radiation


  • Alpha
  • Beta
  • Gamma
• The half-life is the time taken for the activity to halve
• Nuclear fusion - two smaller nuclei fuse to create one larger nucleus
• Reactor Feature

  • Control rods - absorbs neutrons
  • Moderator - slows down neutrons
  • Shielding - Absorb radiation from fission products
• Nuclear fusion releases more energy than fission
• Uses of radiation | Alpha: Smoke detector | Beta: Thickness of aluminium foil | Gamma: Sterilising |
• What is alpha radiation? two protons and two neutrons / helium nucleus
• What is beta radiation? an electron
• What is gamma radiation? An electromagnetic wave
• Penetrating power | (Low) Alpha | Beta | (High) Gamma
• Ionising ability | (high) Alpha | Beta | (low) Gamma
• Radioactive decay | Alpha - emits an alpha particle, becomes a different element with one less mass number and atomic number | Beta - emits a beta particle, becomes a different element with the same mass number but one more or less than the original atom's atomic number | Gamma - no change to the elements mass number or atomic number
• Alpha particles are stopped by paper
• Beta particles can be stopped by aluminium foil
• Gamma rays can only be stopped by lead
• What is background radiation?

  Radiation all around us from natural and artificial sources E.G cosmic rays, rocks, food
• Decay Equations

  Alpha - 4/2

  Beta - 0/-1

  Gamma - 0/0
• Element information

  top number = mass number (P+N)

  bottom number = Atomic number (P)
• How do you find how many neutrons an element has?

  Mass number - Atomic number = N
• What is a chain reaction?

  three neutrons released from one fission event and can split into three other uranium nuclei