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Chapter 4 Nuclear Chemistry

Chapter 4 Nuclear Chemistry. 4.2 Nuclear Equations. Alpha Decay. When a radioactive nucleus emits an alpha particle, a new nucleus forms that has a mass number 4 less than that of the initial nucleus an atomic number that has decreased by 2 from that of the initial nucleus.

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Chapter 4 Nuclear Chemistry

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  1. Chapter 4 Nuclear Chemistry 4.2 Nuclear Equations

  2. Alpha Decay When a radioactive nucleus emits an alpha particle, a new nucleus forms that has • a mass number 4 less than that of the initial nucleus • an atomic number that has decreased by 2 from that of the initial nucleus

  3. Completing Nuclear Equations In a completed nuclear equation, the • sum of the mass numbers of the unstable isotope and the products are equal • sum of the atomic numbers of the unstable isotope and the products are equal Sum of Mass Numbers 251 = 251 251Cf 247Cm+ 4He 98 96 2 98 = 98 Sum of Atomic Numbers

  4. Guide to Completing a Nuclear Equation

  5. Equation for Alpha Decay Write an equation for the alpha decay of 222Rn. STEP 1Write the incomplete equation: STEP 2Determine the mass number:222 – 4 = 218 STEP 3Determine the atomic number: 86 – 2 = 84 STEP 4Determine the symbol of element:84 = Po STEP 5Complete the equation: 84 Po 85 At 86 Rn

  6. Beta Decay A beta particle • is an electron emitted from the nucleus • forms when a neutron in the nucleus breaks down

  7. Equation for a Beta Emitter STEP 1Write an equationfor the decay of K42 (potassium-42), a beta emitter. STEP 2Mass number:(same) = 42 STEP 3Atomic number: 19 + 1 = 20 STEP 4Symbol of element:20 = Ca STEP 5Complete the equation: 19 K 20 Ca

  8. Learning Check Write the nuclear equation for the beta decay of Co-60.

  9. Solution beta particle

  10. Positron Emission In positron emission, • a proton is converted to a neutron and a positron • the mass number of the new nucleus is the same, but the atomic number decreases by 1

  11. Gamma Radiation In gamma radiation, • energy is emitted from an unstable nucleus, indicated by m following the mass number • the mass number and the atomic number of the new nucleus are for the same element

  12. Summary of Types of Radiation

  13. Changes in Mass and Atomic Numbers

  14. Producing Radioactive Isotopes Radioactive isotopes are produced • when a stable nucleus is converted to a radioactive nucleus by bombarding it with a small particle • in a process called transmutation

  15. Learning Check What radioactive isotope is produced when a neutron bombards 59Co?

  16. Solution Sum of mass numbers 60 = 60 27 = 27 Sum of atomic numbers

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