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Part I: Chapter 25 Radioactive decay & Half Life. Dr. Williams JCHS. The Nucleus. Nucleus Size. Nuclear Forces. Nucleus Stability. Nucleus Splitting. Transmutation. Transmutation. + charge. 0 charge. Characteristics of Radiation Types pg. 801. Natural Transmutation.
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Part I: Chapter 25Radioactive decay & Half Life Dr. Williams JCHS
+ charge 0 charge
Natural Transmutation • Just as a balanced chemical reaction must always be written for a “normal” chemical reaction a balanced nuclear reaction can be written as well. These are examples of balanced nuclear equations One element becomes another The particles involved are balanced The sum of the mass numbers and the sum of the atomic numbers on each side are equal
Natural Transmutation Steps for writing and balancing a nuclear reaction Sample: Write and balance the nuclear reaction for radium-226. Step 1:Write the notation for the radioactive isotope as the reactant Step 2: Look on Table N for the decay mode of the radioisotope radium – 226 = α Step 3: Look on Table O for the symbol of the decay mode. This is one of the products, write the symbol of the particle as a product Step 4: The second product is determined by first balancing the mass number and atomic number and then looking on the periodic table to determine what element has that atomic number 226 222 4 Rn Ra He + 2 86 88
Natural Transmutation • Write the balanced nuclear equation for the decay of iodine - 131 131 131 I 0 β Xe + 53 -1 54
Natural Transmutation • Neon – 19 decays by positron emission. Write the balanced nuclear equation. 19 Ne 0 β 19 F + 10 +1 9
Practice with Alpha Particles Alpha decay can most simply be described like this: 1) The nucleus of an atom splits into two parts. 2) One of these parts (the alpha particle) goes zooming off into space. 3) The nucleus left behind has its atomic number reduced by 2 and its mass number reduced by 4 (that is, by 2 protons and 2 neutrons). There are other points, but the three above are enough for this class. Here is a typical alpha decay equation:
Beta Practice Beta decay is somewhat more complex than alpha decay is. These points present a simplified view of what beta decay actually is: 1) A neutron inside the nucleus of an atom breaks down, changing into a proton. 2) It emits an electron and an anti-neutrino (more on this later) which go zooming off into space. 3) The atomic number goes UP by one and mass number remains unchanged. Here is an example of a beta decay equation:
