Chemistry - Nuclear

• Protons have a mass number of one and carry a positive charge.
• Main purpose of radioactivity is to change a little mass into a lot of energy
• Nuclear reactions release much greater amounts of energy than chemical reactions
• Mass of reactants is greater than mass of products
• Ratio of neutrons to protons determines the stability of an isotope
• Natural Transmutation is when one single nucleus spontaneously decays. It has only one reactant.
• Artificial Transmutation is when a nucleus is bombarded with high-energy particles to change from one element to another. It has two reactants.
• Examples:

  • 131 I: used to treat/diagnose thyroid disorders
  • 14 C - 12C: used to date the age of things that were once alive
  • 238 U - 206 Pb: used to date things that were never alive
  • 60 Co: used in cancer/radiation therapy
  • 14 C: used as radioactive tracers
  • 99 Tc: used to image the body/detect tumors
  • 60 Co and 137 Cs: used to kill bacteria in food
• Fission Reactions:

  • The splitting of a heavy nucleus into lighter nuclei
  • Involves capturing, then splitting, a neutron
  • Produces 2 nuclei, neutrons, and a large amount of energy
  • Products are heavily radioactive
• Fusion:

  • The combining of light nuclei into heavier nuclei
  • Products are NOT highly radioactive
• The ratio of neutrons to protons determines the stability of any nucleus.
• Natural transmutations include alpha decay (alpha emission), beta minus decay (beta emission) and gamma radiation.
• Artificial transmutations are induced by the bombardment of the nucleus in high-energy particles.
• Nuclei of elements with equal amounts of neutrons and protons (ratio of 1:1) are generally stable and will not undergo spontaneous decay.
• The nucleus is unstable if the neutron:proton ratio is less than 1:1 or greater than 1.5:1
• A carbon-14 nucleus contains two extra neutrons that make it unstable and radioactive.
• Hydrogen-1 has a ratio of 0:1 but is still stable.
• Natural transmutation includes: 1 - alpha, beta, positron emission, 2 - sun, 3 - electron capture.
• Induced/Artificial Transmutation includes: the bombardment of any nucleus, fusion (uniting nuclei/atoms), fission (splitting the nucleus)
• A particle accelerator causes artificial transmutation; high kinetic energy is needed to overcome the repulsion b/w charged particles and the nucleus
• A particle accelerator can increase the kinetic energy of: 1) alpha and beta particle, 2) alpha particle and neutron, 3) gamma ray and beta particle, 4) neutron and gamma ray

  1) alpha and beta particle
• Gamma rays are pure energy - therefore not a charged particle.
• Symbol, mass, charge, ionizing radiation, and needed shielding for alpha particle?

  a/He, 4, 2, least penetrating (most ionizing), paper
• Symbol, mass, charge, ionizing radiation, and needed shielding for beta particle

  B/e-, 0, -1, middle, tin foil
• Symbol, mass, charge, ionizing radiation, and needed shielding for positron

  B+/e+, 0, -1, middle, tin foil
• Symbol, mass, charge, ionizing radiation, and needed shielding for gamma rays 


  γ, 0, 0, most penetrating (least ionizing), led + concrete
• MOST penetrating means...

  LEAST ionizing
• Mass defect - the energy released during nuclear reactions is much greater than the energy released during chemical reactions.
• Which nuclear radiation is similar to high energy x-ray?

  gamma
• A change in the nucleus of an atoms that converts it from one element to another is called a transmutation. It can occur naturally or artificially.