CHEM 2

• Nuclear stability


  The nucleus of an element is stable and thus it does not decay spontaneously emitting any kind of radioactivity
• Radiation


  Energy given off by matter in the form of rays or high-speed particles
• Made up of a nucleus containing protons and neutrons, and an outer shell containing electrons
• The nucleus carries a positive electrical charge


  The electrons carry a negative electrical charge
• The forces within the atom

  Work toward a strong, stable balance by getting rid of excess atomic energy (radioactivity)
• Radioactivity


  The spontaneous emission of energy from unstable nuclei
• Physical forms of radiation

  • Electromagnetic radiation (e.g. sunlight, x-rays, radar, radio waves)
  • Particle radiation (e.g. alpha particles, beta particles, neutrons)
• Electromagnetic radiation


  Pure energy with no weight, in the form of vibrating or pulsating rays or "waves" of electrical and magnetic energy
• Particle radiation


  Tiny fast-moving particles that have both energy and mass (weight)
• Particle radiation types


  • Alpha particles
  • Beta particles
  • Neutrons
• Radioactive decay


  Unstable atoms emit radiation (alpha particles, beta particles, gamma rays, x-rays) to become more stable
• Nuclear fission


  The splitting of a nucleus, usually of uranium-235, resulting in the release of energy, radiation, and neutrons
• Fissile materials


  Elements whose nuclei can split as a result of absorbing an additional neutron
• Ionizing radiation


  Radiation that has sufficient energy to break molecular bonds or remove electrons from atoms
• Non-ionizing radiation


  Radiation that deposits energy in materials but does not have sufficient energy to break molecular bonds or remove electrons
• Alpha particles


  Charged particles emitted from naturally occurring and man-made radioactive materials, used in smoke detectors
• Beta particles


  Electron-like particles emitted from naturally occurring radioactive materials, used in medical applications
• Gamma rays and x-rays


  High-energy waves that can travel great distances and penetrate materials, used in medical applications to treat cancer and sterilize instruments
• Electron


  Negatively charged particle with a charge of -1.602 × 10^-19 coulombs
• Positron


  Positively charged antiparticle of the electron, with a charge of +1.602 × 10^-19 coulombs