Chapter 19 The Nucleus: A Chemist’s View AP*

AP Learning Objectives  LO 4.3 The student is able to connect the half-life of a reaction to the rate constant of a first-order reaction and justify the use of this relation in terms of the reaction being a first-order reaction. (Sec 19.2, 19.4)

Section 19.1 Nuclear Stability and Radioactive Decay Copyright © Cengage Learning. All rights reserved 3 Review  Atomic Number (Z) – number of protons  Mass Number (A) – sum of protons and neutrons

Section 19.1 Nuclear Stability and Radioactive Decay Copyright © Cengage Learning. All rights reserved 4 Radioactive Decay  Nucleus undergoes decomposition to form a different nucleus.

Section 19.1 Nuclear Stability and Radioactive Decay Copyright © Cengage Learning. All rights reserved 5 Radioactive Stability  Nuclides with 84 or more protons are unstable.  Light nuclides are stable when Z equals A – Z (neutron/proton ratio is 1).  For heavier elements the neutron/proton ratio required for stability is greater than 1 and increases with Z.

Section 19.1 Nuclear Stability and Radioactive Decay Copyright © Cengage Learning. All rights reserved 6 Radioactive Stability  Certain combinations of protons and neutrons seem to confer special stability.  Even numbers of protons and neutrons are more often stable than those with odd numbers.

Section 19.1 Nuclear Stability and Radioactive Decay Copyright © Cengage Learning. All rights reserved 7 Radioactive Stability  Certain specific numbers of protons or neutrons produce especially stable nuclides.  2, 8, 20, 28, 50, 82, and 126

Section 19.1 Nuclear Stability and Radioactive Decay Copyright © Cengage Learning. All rights reserved 8 The Zone of Stability

Section 19.1 Nuclear Stability and Radioactive Decay Copyright © Cengage Learning. All rights reserved 9 Types of Radioactive Decay  Alpha production (α):  Beta production (β):

Section 19.1 Nuclear Stability and Radioactive Decay Copyright © Cengage Learning. All rights reserved 10 Types of Radioactive Decay  Gamma ray production (γ):  Positron production:

Section 19.1 Nuclear Stability and Radioactive Decay Copyright © Cengage Learning. All rights reserved 11 Types of Radioactive Decay  Electron capture: Inner-orbital electron

Section 19.1 Nuclear Stability and Radioactive Decay Copyright © Cengage Learning. All rights reserved 12 Decay Series (Series of Alpha and Beta Decays)

Section 19.1 Nuclear Stability and Radioactive Decay Copyright © Cengage Learning. All rights reserved 13 Which of the following produces a particle? electron capture positron alpha particle beta particle CONCEPT CHECK!

Section 19.2 The Kinetics of Radioactive Decay AP Learning Objectives, Margin Notes and References  Learning Objectives  LO 4.3 The student is able to connect the half-life of a reaction to the rate constant of a first-order reaction and justify the use of this relation in terms of the reaction being a first-order reaction.

Section 19.2 The Kinetics of Radioactive Decay Rate of Decay Rate = kN  The rate of decay is proportional to the number of nuclides. This represents a first-order process. Copyright © Cengage Learning. All rights reserved 15

Section 19.2 The Kinetics of Radioactive Decay Half-Life  Time required for the number of nuclides to reach half the original value. Copyright © Cengage Learning. All rights reserved 16

Section 19.2 The Kinetics of Radioactive Decay Nuclear Particles Copyright © Cengage Learning. All rights reserved 17 To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERECLICK HERE

Section 19.2 The Kinetics of Radioactive Decay Half-Life of Nuclear Decay Copyright © Cengage Learning. All rights reserved 18 To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERECLICK HERE

Section 19.2 The Kinetics of Radioactive Decay A first order reaction is 35% complete at the end of 55 minutes. What is the value of k? k = 7.8 × min -1 EXERCISE!

Section 19.3 Nuclear Transformations Nuclear Transformation  The change of one element into another. Copyright © Cengage Learning. All rights reserved 20

Section 19.3 Nuclear Transformations A Schematic Diagram of a Cyclotron 21

Section 19.3 Nuclear Transformations A Schematic Diagram of a Linear Accelerator Copyright © Cengage Learning. All rights reserved 22

Section 19.4 Detection and Uses of Radioactivity AP Learning Objectives, Margin Notes and References  Learning Objectives  LO 4.3 The student is able to connect the half-life of a reaction to the rate constant of a first-order reaction and justify the use of this relation in terms of the reaction being a first-order reaction.

Section 19.4 Detection and Uses of Radioactivity Measuring Radioactivity Levels  Geiger counter  Scintillation counter Copyright © Cengage Learning. All rights reserved 24

Section 19.4 Detection and Uses of Radioactivity Geiger Counter Copyright © Cengage Learning. All rights reserved 25 To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERECLICK HERE

Section 19.4 Detection and Uses of Radioactivity Carbon–14 Dating  Used to date wood and cloth artifacts.  Based on carbon – 14 to carbon – 12 ratio. Copyright © Cengage Learning. All rights reserved 26

Section 19.4 Detection and Uses of Radioactivity Radiotracers  Radioactive nuclides that are introduced into organisms in food or drugs and whose pathways can be traced by monitoring their radioactivity. Copyright © Cengage Learning. All rights reserved 27

Section 19.4 Detection and Uses of Radioactivity Radiotracers Copyright © Cengage Learning. All rights reserved 28

Section 19.5 Thermodynamic Stability of the Nucleus Energy and Mass  When a system gains or loses energy it also gains or loses a quantity of mass. E = mc 2 Copyright © Cengage Learning. All rights reserved 29 Δm = mass defect ΔE = change in energy  If ΔE is negative (exothermic), mass is lost from the system.

Section 19.5 Thermodynamic Stability of the Nucleus Mass Defect (Δm)  Calculating the mass defect for :  Since atomic masses include the masses of the electrons, we must account for the electron mass.  nucleus is “synthesized” from 2 protons and two neutrons. 30

Section 19.5 Thermodynamic Stability of the Nucleus Binding Energy  The energy required to decompose the nucleus into its components.  Iron-56 is the most stable nucleus and has a binding energy of 8.79 MeV. Copyright © Cengage Learning. All rights reserved 31

Section 19.5 Thermodynamic Stability of the Nucleus Binding Energy per Nucleon vs. Mass Number Copyright © Cengage Learning. All rights reserved 32

Section 19.6 Nuclear Fission and Nuclear Fusion 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 © Cengage Learning. All rights reserved 33

Section 19.6 Nuclear Fission and Nuclear Fusion Nuclear Fission Copyright © Cengage Learning. All rights reserved 34 To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERECLICK HERE

Section 19.6 Nuclear Fission and Nuclear Fusion Fission Processes  A self-sustaining fission process is called a chain reaction. Copyright © Cengage Learning. All rights reserved 35

Section 19.6 Nuclear Fission and Nuclear Fusion Schematic Diagram of a Nuclear Power Plant Copyright © Cengage Learning. All rights reserved 36

Section 19.6 Nuclear Fission and Nuclear Fusion Schematic Diagram of a Reactor Core Copyright © Cengage Learning. All rights reserved 37

Section 19.6 Nuclear Fission and Nuclear Fusion Nuclear Fusion Copyright © Cengage Learning. All rights reserved 38 To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERECLICK HERE

Section 19.7 Effects of Radiation Biological Effects of Radiation Depend on: 1.Energy of the radiation 2.Penetrating ability of the radiation 3.Ionizing ability of the radiation 4.Chemical properties of the radiation source Copyright © Cengage Learning. All rights reserved 39

Section 19.7 Effects of Radiation rem (roentgen equivalent for man)  The energy dose of the radiation and its effectiveness in causing biologic damage must be taken into account. Number of rems = (number of rads) × RBE rads = radiation absorbed dose RBE = relative effectiveness of the radiation in causing biologic damage 40

Section 19.7 Effects of Radiation Effects of Short-Term Exposures to Radiation Copyright © Cengage Learning. All rights reserved 41