Lecture 25.2- Nuclear Transformations
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Lecture 25.2- Nuclear Transformations

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Section 25.2 Lecture for Honors & Prep

Section 25.2 Lecture for Honors & Prep

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Lecture 25.2- Nuclear Transformations Lecture 25.2- Nuclear Transformations Presentation Transcript

  • BELLWORK
    • What is the symbol for an alpha particle?
    • Write the nuclear equation for the alpha decay of Uranium-238.
    • What is the symbol of a beta particle?
    • Write the nuclear equation for the beta decay of Carbon-14.
    • Write the symbol for gamma radiation.
    • Why is gamma radiation often not included in a nuclear equation?
  • Damage from nuclear radiation is due to ionization of living tissue.
    • Nuclear radiation is called ionizing radiation because it produces ions from neutral molecules.
    • Alpha radiation has a low penetration, but it is the most damaging to living tissue because it deposits all its energy along a short path
  • Lecture 25.2- Nuclear Transformations
    • Radon-222 is a radioactive isotope that is present naturally in the soil in some areas. It has a constant rate of decay. You will learn about decay rates of radioactive substances.
    25.2
  • The nucleus is held together by the strong nuclear force
    • The strong nuclear force is the strongest force known
    • Protons and neutrons are very close together
    • They exchange a teeny bit of mass back and forth.
    • When disrupted, the mass is converted to energy according to
    • E=mc 2
    • The mass is tiny.
    • The energy is immense.
  • Protons and neutrons experience the strong nuclear force if close enough Because protons repel each other the nucleus needs a certain proton to neutron ratio for stability
        • More than 1,500 different nuclei are known. Of those, only 264 are stable and do not decay or change with time. These nuclei are in a region called the band of stability .
    25.2
  • Nuclear Stability and Decay
        • The neutron-to-proton ratio determines the type of decay that occurs.
    25.2
        • A half-life (t 1/2 ) is the time required for one-half of the nuclei of a radioisotope sample to decay to products.
          • After each half-life, half of the existing radioactive atoms have decayed into atoms of a new element .
    25.2
  • 25.2
  • 25.2
  • 25.2 Stable Isotope
        • The ratio of Carbon-14 to stable carbon in the remains of an organism changes in a predictable way that enables the archaeologist to obtain an estimate of its age.
    25.2
  • 25.1
  • 25.1
  • 25.1
  • 25.1
  • for Sample Problem 25.1
        • The conversion of an atom of one element to an atom of another element is called transmutation .
          • Transmutation can occur by radioactive decay.
          • Or
          • when particles bombard the nucleus of an atom.
    25.2
        • The first artificial transmutation reaction involved bombarding nitrogen gas with alpha particles.
    25.2
        • The elements in the periodic table with atomic numbers above 92, the atomic number of uranium, are called the transuranium elements.
            • All transuranium elements undergo transmutation.
            • None of the transuranium elements occur in nature, and all of them are radioactive.
    25.2
        • Transuranium elements are synthesized in nuclear reactors and nuclear accelerators.
    25.2
  • 25.2 Section Quiz.
      • 1. During nuclear decay, if the atomic number decreases by one but the mass number is unchanged, the radiation emitted is
        • a positron.
        • an alpha particle.
        • a neutron.
        • a proton.
  • 25.2 Section Quiz.
      • 2. When potassium-40 (atomic number 19) decays into calcium-40 (atomic number 20), the process can be described as
        • positron emission.
        • alpha emission.
        • beta emission.
        • electron capture.
  • 25.2 Section Quiz.
      • 3. If there were 128 grams of radioactive material initially, what mass remains after four half-lives?
        • 4 grams
        • 32 grams
        • 16 grams
        • 8 grams
  • 25.2 Section Quiz.
      • 4. When transmutation occurs, the ________ always changes.
        • number of electrons
        • mass number
        • atomic number
        • number of neutrons
  • 25.2 Section Quiz
      • 5. Transmutation occurs by radioactive decay and also by
        • extreme heating.
        • chemical reaction.
        • high intensity electrical discharge.
        • particle bombardment of the nucleus.