Copyright©2000 by Houghton Mifflin Company. All rights reserved. 1 Chapter 18 (DP) Chapter 28 (Honors Regents) The Nucleus: A Chemist’s View

The zone of stability.

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4 Characteristics of Some Ionizing Radiations

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6 Effect of Charge on Nuclear Particles

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 7 Nuclear Transmutation (artificial shown here) The change of one element into another.

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 8 Types of Radioactive Decay (natural transmutation) alpha production (  ): helium nucleus, beta production (  ):

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 9 More Types of Radioactive Decay (natural transmutation) gamma ray production (  ): positron production:

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 10 Check Regents Table O for Nuclear Chemistry Symbols!!!

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 11 Practice Balancing Nuclear Rxns

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 12 Decay Series A radioactive nucleus reaches a stable state by a series of steps.

The decay series from U to Pb

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 14 Rate of Decay rate = kN The rate of decay is proportional to the number of nuclides. This represents a first- order process.

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 15 Half-Life...the time required for the number of nuclides to reach half the original value (N 0 /2). Check Regents Reference Table N for Half-Lives!

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 16 Simplified Half-Life Equation: Where A 0 = original sample mass A = final sample mass n = number of half-lives

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 17 The decay of a 10.0-g sample of strontium-90 over time. Note that the half-life is a constant 28.8 years.

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 18 The change in the amount of Mo with time (t 1/2 = 67 h)

19

Researcher taking a bone sample for carbon-14 dating at an archeological site in Egypt.

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 21 Schematic diagram of a linear accelerator. Atom “Smashers”

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 22 A schematic diagram of a cyclotron.

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Copyright©2000 by Houghton Mifflin Company. All rights reserved. 24 An aerial view of Fermilab, a high energy particle accelerator in Batavia, Illinois.

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 25 Energy and Mass  m = mass defect  E = change in energy If  E =  (exothermic), mass is lost from the system. When a system gains or loses energy it also gains or loses a quantity of mass.  E =  mc 2

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 26 Nuclear Fission and Fusion Fusion: Combining two light nuclei to form a heavier, more stable nucleus. Fission: Splitting a heavy nucleus into two nuclei with smaller mass numbers.

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 27 Fission Processes A self-sustaining fission process is called a chain reaction.

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 28 On capturing a neutron, the nucleus undergoes fission to produce two lighter nuclides, free neutrons (typically three), and a large amount of energy.

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 29 Representation of a fission process in which each event produces two neutrons, which can go on to split other nuclei, leading to a self-sustaining chain reaction.

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 30 If the mass of fissionable material is too small, most of the neutrons escape before causing another fission event, and the process dies out.

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 31 Key Parts of a Fission Reactor 4 Coolant (deuterium oxide = heavy water or molten sodium) 4 Containment Shell (concrete & lead) Reactor Core: 3% U-235 plus moderator + control rods Moderator (slows down neutrons – carbon or D 2 O) Control Rods (captures neutrons - cadmium based steel)

A schematic of a reactor core. The position of the control rods determines the level of energy production by regulating the amount of fission taking place.

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 33 A schematic diagram of a nuclear power plant.

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 34 Breeder Reactors Fissionable fuel is produced while the reactor runs ( is split, giving neutrons for the creation of ):

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Copyright©2000 by Houghton Mifflin Company. All rights reserved. 37 Biological Effects of Radiation... depend on: 1.Energy of the radiation 2.Penetration ability of the radiation 3.Ionizing ability of the radiation 4.Chemical properties of the radiation source

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 38 A schematic representation of a Geiger-Müller counter.

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 39 After consumption of Na 131 l, the patient's thyroid is scanned for radioactivity levels to determine the efficiency of iodine absorption. (left) A normal thyroid. (right) An enlarged thyroid.

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 40 The two models for radiation damage. In the linear model, even a small dosage causes a proportional risk. In the threshold model, risk begins only after a certain dosage.

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Copyright©2000 by Houghton Mifflin Company. All rights reserved. 45 Ionizing Radiation Used to Cure Cancer

Copyright©2000 by Houghton Mifflin Company. All rights reserved. 46 Skin Cancer From Sunlight