PhySci

• Orbital


  • Nucleus
  • Proton
  • Neutron
  • Electron
• Atom


  • The building blocks of matter
  • Smallest unit of an element
• Nuclear reactions


  Processes in which a nucleus either combines with another nucleus (fusion) or splits into smaller nuclei (fission)
• Types of nuclear reactions

  • Fusion
  • Fission
• The Big Bang is an expansion of the space
• As the universe expands, it cools
• The more energetic the particles are, the higher the temperature will be
• The identity of the elements depends on how many protons it has
• Isotopes


  Chemical elements that have the same number of protons but different number of neutrons (greater or lesser atomic mass) than the standard for that element
• Star


  A very hot ball of gas (plasma)
• Nuclear fusion


  Occurs at 15,000,000°C
• Stars much larger than our Sun can fuse heavier elements from lighter elements
• As you proceed deeper into the star, temperatures and pressures increase, and heavier and heavier nuclei are fused together
• Iron is the heaviest element that can be made in a star
• Elements heavier than iron have fusion reactions with temperature and pressure requirements greater than those that can occur within the core of a giant star
• Supernova


  Explosion of a star
• When a star runs out of nuclear fuel (lighter nuclei) and can no longer undergo fusion reactions, gravity causes the star to collapse
• The explosion of the star momentarily generates high enough temperatures and pressures to cause nuclear fusion reactions that make elements with atomic numbers 27-92 (Cobalt to Uranium)
• Since only the largest stars can explode in supernovae events, elements with atomic numbers 27-92 are rarer than elements with atomic numbers 1-26
• Types of supernova nucleosynthesis

  • Neutron
  • Slow Neutron Capture
  • Rapid Neutron Capture
  • Proton Capture
• Dobereiner's Triad


  Elements were grouped into three according to their atomic masses
• Newlands Octaves


  Elements arranged in increasing atomic masses every eighth
• Mendeleev Periodic Table


  The physical and chemical properties of elements are a periodic function of their atomic masses
• Modern Periodic Law


  The physical and chemical properties of elements are a periodic function of their atomic numbers
• Nuclear transmutation


  A reaction involving the transformation of one element or isotope into another element
• Discovery of element 43 (Technetium)


  1937
• Discovery of element 43 (Technetium)


  Ernest Lawrence synthesized it by bombarding molybdenum (Z=42) with fast-moving neutrons
• Discovery of element 61 (Promethium)

  1945
• Discovery of element 61 (Promethium)


  Discovered as a decay product of the fission of uranium
• Discovery of element 85 (Astatine)


  1940
• Discovery of element 85 (Astatine)


  Dale Corson, Kenneth Mackenzie, and Emilio Segre discovered it by bombarding atoms of bismuth (Z=83) with fast-moving alpha particles in a cyclotron
• Discovery of element 87 (Francium)


  1939
• Discovery of element 87 (Francium)


  Discovered as a decay product of the fission of actinium