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2. Standardized Test Prep
Resources
Chapter Presentation
Bellringers
Transparencies
Standardized Test Prep
Math Skills
Visual Concepts

3. Chapter 9 Table of Contents Section 1 What Is Radioactivity?
Nuclear Changes
Table of Contents
Section 1 What Is Radioactivity?
Section 2 Nuclear Fission and Fusion
Section 3 Nuclear Radiation Today

4. Chapter 9
Section 1 What Is Radioactivity?
Objectives
Identify four types of nuclear radiation and their properties.
Balance equations for nuclear decay.
Calculate the half-life of a radioactive isotope.

5. Chapter 9
Section 1 What Is Radioactivity?
Bellringer
Before studying about nuclear chemistry, answer the following items to refresh your memory about the structure of the nucleus.
1. Label the diagram shown below.

6. Chapter 9 Bellringer, continued Section 1 What Is Radioactivity?
2. Complete the table to indicate how many protons and neutrons are in the nuclei of the following atoms:

7. Chapter 9 Nuclear Radiation
Section 1 What Is Radioactivity?
Nuclear Radiation
The process by which an unstable nucleus emits one or more particles or energy in the form of electromagnetic radiation is called radioactivity.
The particles that are released from the nucleus during radioactive decay is called nuclear radiation.
There are different types of nuclear radiation.

8. Types of Nuclear Radiation
Chapter 9
Section 1 What Is Radioactivity?
Types of Nuclear Radiation

9. Comparing Alpha, Beta, and Gamma Particles
Chapter 9
Section 1 What Is Radioactivity?
Comparing Alpha, Beta, and Gamma Particles
Click below to watch the Visual Concept.
Visual Concept

10. Nuclear Radiation, continued
Chapter 9
Section 1 What Is Radioactivity?
Nuclear Radiation, continued
Alpha particles consist of protons and neutrons.
An alpha particle is a positively charged atom that is released in the disintegration of radioactive elements and that consists of two protons and two neutrons.
Beta particles are electrons produced from neutron decay.
A beta particle is a charged electron emitted during certain types of radioactive decay, such as beta decay.

11. Nuclear Radiation, continued
Chapter 9
Section 1 What Is Radioactivity?
Nuclear Radiation, continued
Gamma rays are very high energy.
A gamma ray is a high-energy photon emitted by a nucleus during fission and radioactive decay.
Neutron radioactivity may occur in unstable nucleus.
Neutron emission consists of matter that is emitted from an unstable nucleus.
Neutrons are able to travel farther through matter than either alpha or beta particles.

12. Chapter 9
Section 1 What Is Radioactivity?
Nuclear Decay
In nuclear decay, the sums of the mass numbers and the atomic numbers of the decay products equal the mass number and atomic number of the decaying nucleus.
A nucleus gives up two protons and two neutrons during alpha decay.
The process of the alpha decay of radium-226 is written as follows.

13. Nuclear Decay, continued
Chapter 9
Section 1 What Is Radioactivity?
Nuclear Decay, continued
A nucleus gains a proton and loses a neutron during beta decay.
A beta decay process occurs when carbon-14 decays to nitrogen-14 by emitting a beta particle.

14. Alpha, Beta, and Gamma Radiation
Chapter 9
Section 1 What Is Radioactivity?
Alpha, Beta, and Gamma Radiation
Click below to watch the Visual Concept.
Visual Concept

15. Chapter 9
Section 1 What Is Radioactivity?
Math Skills
Nuclear Decay Actinium-217 decays by releasing an alpha particle. Write the equation for this decay process, and determine what element is formed.
1. Write down the equation with the original element on the left side and the products on the right side.
Use the letter X to denote the unknown product. Note that the mass and atomic numbers of the unknown isotope are represented by the letters A and Z.

16. Chapter 9 Math Skills, continued
Section 1 What Is Radioactivity?
Math Skills, continued
2. Write math equations for the atomic and mass numbers.
217 = A – = Z – 2
3. Rearrange the equations.
A = 217 – 4 Z = 89 – 2
4. Solve for the unknown values, and rewrite the equation with all nuclei represented.
A = Z = 87
The unknown decay product has an atomic number of 87, which is francium, according to the periodic table. The element is therefore

17. Radioactive Decay Rates
Chapter 9
Section 1 What Is Radioactivity?
Radioactive Decay Rates
The half-life is the time required for half of a sample of a radioactive substance to disintegrate by radioactive decay or by natural processes.
Half-life is a measure of how quickly a substance decays.
Using half-lives, scientist can predict how old an object is.
Carbon-14 is used to date materials.

18. Chapter 9
Section 1 What Is Radioactivity?
Half-Life

19. Chapter 9 Half-Life Section 1 What Is Radioactivity?
Click below to watch the Visual Concept.
Visual Concept

20. Chapter 9
Section 1 What Is Radioactivity?
Math Skills
Half-life Radium-226 has a half-life of 1599 years. How long would it take seven-eighths of a radium-226 sample to decay?
1. List the given and unknown values.
Given: half-life = 1599 years
fraction of sample decayed = 7/8
Unknown: fraction of sample remaining = ?
total time of decay = ?

21. Chapter 9 Math Skills, continued
Section 1 What Is Radioactivity?
Math Skills, continued
2. Calculate the fraction of radioactive sample remaining.
To find the fraction of sample remaining, subtract the fraction that has decayed from 1.
3. Calculate the number of half-lives.

22. Chapter 9 Math Skills, continued
Section 1 What Is Radioactivity?
Math Skills, continued
3. Calculate the number of half-lives (continued).
Three half-lives are needed for one-eighth of the sample to remain undecayed.
4. Calculate the total time required for the radio-active decay.
Each half-life lasts 1599 years.

23. Section 2 Nuclear Fission and Fusion
Chapter 9
Objectives
Describe how the strong nuclear force affects the composition of a nucleus.
Distinguish between fission and fusion, and provide examples of each.
Recognize the equivalence of mass and energy, and why small losses in mass release large amounts of energy.
Explain what a chain reaction is, how one is initiated, and how it can be controlled.

24. Section 2 Nuclear Fission and Fusion
Chapter 9
Bellringer
In your study of chemical reactions, you learned that one convenient way to classify reactions was as synthesis or decomposition. In synthesis reactions, the products are larger and more complex than the reactants. In decomposition reactions, the opposite is true.
In some situations, nuclear reactions can occur. These reactions can also be categorized by how the product nuclei compare to the reactant nuclei. Study the models of the nuclei shown below and answer the following items:

25. Section 2 Nuclear Fission and Fusion
Chapter 9
Bellringer, continued

26. Chapter 9 Bellringer, continued
Section 2 Nuclear Fission and Fusion
Chapter 9
Bellringer, continued
1. In which of the diagrams did a complex nucleus form simpler nuclei?
2. In which of the diagrams did simple nuclei combine to form a complex nucleus?
3. Each year, scientists around the world attempt to “discover” new elements using nuclear reactions. Which of the reactions shown in the diagrams above would be most likely to be useful for this type of research? Explain your answer.

27. Chapter 9 Nuclear Forces Nuclei are held together by a special force.
Section 2 Nuclear Fission and Fusion
Chapter 9
Nuclear Forces
Nuclei are held together by a special force.
Protons and neutrons are tightly packed in the tiny nucleus of an atom.
The strong nuclear force causes protons and neutrons in the nucleus to attract each other. This attraction is much stronger than the electric repulsion between protons.
Neutrons contribute to nuclear stability.
Too many neutrons or protons can cause a nucleus to become unstable and decay.

28. Section 2 Nuclear Fission and Fusion
Chapter 9
Forces in the Nucleus

29. Chapter 9 Nuclear Fission
Section 2 Nuclear Fission and Fusion
Chapter 9
Nuclear Fission
Fission is the process by which a nucleus splits into two or more fragments and releases neutrons and energy.
One type of fission of uranium-235 can be repre-sented by the following equation.

30. Chapter 9 Nuclear Fission Section 2 Nuclear Fission and Fusion
Click below to watch the Visual Concept.
Visual Concept

31. Nuclear Fission, continued
Section 2 Nuclear Fission and Fusion
Chapter 9
Nuclear Fission, continued
Energy is released during a nuclear fission.
The equivalence of mass and energy observed in nature is explained by the special theory of relativity.
This equivalence is expressed by the following equation.
Mass-Energy Equation

32. Nuclear Fission, continued
Section 2 Nuclear Fission and Fusion
Chapter 9
Nuclear Fission, continued
Neutrons released by fission can start a chain reaction.
A nuclear chain reaction is a continuous series of nuclear fission reactions.
Chain reactions can be controlled.
If there is less than a critical mass of a fissionable isotope, a chain reaction will not occur.
The critical mass is the minimum mass of a fissionable isotope that provides the number of neutrons needed to sustain a chain reaction.

33. Section 2 Nuclear Fission and Fusion
Chapter 9
Chain Reaction

34. Nuclear Chain Reaction
Section 2 Nuclear Fission and Fusion
Chapter 9
Nuclear Chain Reaction
Click below to watch the Visual Concept.
Visual Concept

35. Chapter 9 Critical Mass Section 2 Nuclear Fission and Fusion
Click below to watch the Visual Concept.
Visual Concept

36. Chapter 9 Nuclear Fusion
Section 2 Nuclear Fission and Fusion
Chapter 9
Nuclear Fusion
Nuclear fusion is the process in which light nuclei combine at extremely high temperature, forming heavier nuclei and releasing energy.
Nuclear fusion occurs in the sun.
Four hydrogen atoms fuse together in a multi-step process to produce a helium atoms and enormous energy in the form of gamma rays.

37. Chapter 9 Nuclear Fusion Section 2 Nuclear Fission and Fusion
Click below to watch the Visual Concept.
Visual Concept

38. Section 3 Nuclear Radiation Today
Chapter 9
Objectives
Describe sources of nuclear radiation, including where it exists as background radiation.
List and explain three beneficial uses and three possible risks of nuclear radiation.
Compare and contrast the advantages and disadvantages of nuclear energy as a power source.

39. Section 3 Nuclear Radiation Today
Chapter 9
Bellringer
Using what you know about radiation and nuclear reactions, answer the items below.
1. Along with a change in the nuclei involved, what other significant change occurs with radiation and nuclear reactions?
2. Radioactive isotopes are sometimes used for tracer studies, which analyze how and where a person’s body takes up a certain element. As the isotope is taken up by the body, the isotope decays, and the radiation it produces can be detected in order to determine where the element is. Based on how deep the different forms of radiation penetrate, do you think that alpha, beta, or gamma radiation is used?

40. Chapter 9 Bellringer, continued
Section 3 Nuclear Radiation Today
Chapter 9
Bellringer, continued
3. In Rutherford’s famous gold-foil experiment, the patterns of deflection of the radiation that he shot at the gold foil led him to believe that the atom must contain a small, positively charged nucleus. Explain why Rutherford used alpha radiation rather than gamma radiation.

41. Chapter 9 Where is Radiation?
Section 3 Nuclear Radiation Today
Chapter 9
Where is Radiation?
Nuclear radiation is all around you. Background radiation is the nuclear radiation that arises naturally from cosmic rays and from radioactive isotopes in the soil and air.
Radiation is measured in units of rems.
A rem is the quantity of ionizing radiation that does as much damage to human tissue as 1 roentgen of high-voltage X rays does.

42. Where is Radiation?, continued
Section 3 Nuclear Radiation Today
Chapter 9
Where is Radiation?, continued
Exposure varies from one location to another.
Some activities add to the amount of nuclear radiation exposure.

43. Beneficial Uses of Nuclear Radiation
Section 3 Nuclear Radiation Today
Chapter 9
Beneficial Uses of Nuclear Radiation
Smoke detectors help to save lives.
In a smoke alarm, a small alpha-emitting isotope detects smoke particles in the air.
Nuclear radiation is used to detect diseases.
A radioactive tracer is a radioactive material that is added to a substance so that its distribution can be detected later.
Radioactive tracers are widely used in medicine.

44. Chapter 9 Radioactive Tracer Section 3 Nuclear Radiation Today
Click below to watch the Visual Concept.
Visual Concept

45. Beneficial Uses of Nuclear Radiation, continued
Section 3 Nuclear Radiation Today
Chapter 9
Beneficial Uses of Nuclear Radiation, continued
Nuclear radiation therapy is used to treat cancer.
Radiotherapy is treatment that uses controlled doses of nuclear radiation for treating diseases such as cancer.
Agriculture uses radioactive tracers and radio-isotopes.
On research farms, radioactive tracers help scientists to understand biochemical processes in plants.

46. MRI Image of a Healthy Brain
Section 3 Nuclear Radiation Today
Chapter 9
MRI Image of a Healthy Brain

47. MRI Image of Brain with Alzheimer’s
Section 3 Nuclear Radiation Today
Chapter 9
MRI Image of Brain with Alzheimer’s

48. Possible Risks of Nuclear Radiation
Section 3 Nuclear Radiation Today
Chapter 9
Possible Risks of Nuclear Radiation
Nuclear radiation can ionize atoms.
Ionization is a change in the number of electrons in an atom or molecule, causing the particle to be positively or negatively charged.
Radiation sickness results from high levels of nuclear radiation.
People working in radioactive areas wear a dosimeter, a device that measures the amount of nuclear radiation exposure.
Studies have shown a relationship between exposure to high levels of nuclear radiation and cancer.

49. Possible Risks of Nuclear Radiation
Section 3 Nuclear Radiation Today
Chapter 9
Possible Risks of Nuclear Radiation
The risk depends upon the amount of radiation exposure.
High concentrations of radon gas can be hazardous.
Radon gas is colorless and odorless, and is produced by the decay of uranium-238 present naturally in soil and rock.
Tests for radon gas are widely available

50. Section 3 Nuclear Radiation Today
Chapter 9
Nuclear Power
Nuclear fission has both advantages and disadvantages.
Nuclear fission is an alternative to fossil fuels as a source of energy.
Radioactive products of fission must be handled carefully and nuclear waste must be safely stored.
Nuclear fusion reactors are being tested.
Nuclear fusion reactions are difficult to produce in the laboratory.
Nuclear fusion also has advantages and disadvantages.

51. Chapter 9 Nuclear Energy Section 3 Nuclear Radiation Today
Click below to watch the Visual Concept.
Visual Concept

52. Section 3 Nuclear Radiation Today
Chapter 9
Concept Map

53. Understanding Concepts
Chapter 9
Standardized Test Prep
Understanding Concepts
1. How can nuclear power plants produce substantial amounts of energy while consuming very little fuel?
A. Radioactive isotopes release a large amount of chemical energy.
B. When large atoms break apart, some of their mass is converted to energy.
C. The bonds between uranium atoms are very strong and release energy when they are broken.
D. A significant amount of energy is released when two atoms come together to form one larger atom.

54. Understanding Concepts, continued
Chapter 9
Standardized Test Prep
Understanding Concepts, continued
1. How can nuclear power plants produce substantial amounts of energy while consuming very little fuel?
A. Radioactive isotopes release a large amount of chemical energy.
B. When large atoms break apart, some of their mass is converted to energy.
C. The bonds between uranium atoms are very strong and release energy when they are broken.
D. A significant amount of energy is released when two atoms come together to form one larger atom.

55. Understanding Concepts, continued
Chapter 9
Standardized Test Prep
Understanding Concepts, continued
2. Why can alpha particles be used safely in home smoke detectors?
F. They are not a type of radiation.
G. They are stopped by material as thin as a sheet of paper.
H. They combine with beta particles in the air to form a neutron.
I. They are harmless even if they come in contact with the human body.

56. Understanding Concepts, continued
Chapter 9
Standardized Test Prep
Understanding Concepts, continued
2. Why can alpha particles be used safely in home smoke detectors?
F. They are not a type of radiation.
G. They are stopped by material as thin as a sheet of paper.
H. They combine with beta particles in the air to form a neutron.
I. They are harmless even if they come in contact with the human body.

57. Understanding Concepts, continued
Chapter 9
Standardized Test Prep
Understanding Concepts, continued
3. When an atom emits a beta particle, how does its mass change?
A. –4
B. –1
C. 0
D. +1

58. Understanding Concepts, continued
Chapter 9
Standardized Test Prep
Understanding Concepts, continued
3. When an atom emits a beta particle, how does its mass change?
A. –4
B. –1
C. 0
D. +1

59. Understanding Concepts, continued
Chapter 9
Standardized Test Prep
Understanding Concepts, continued
4. The nuclei of atoms are made of protons and neutrons. Every atomic nucleus larger than that of hydrogen has at least two positively charged protons. Why do the nuclei remain intact instead of being broken apart by the repulsion of their electric charges?

60. Understanding Concepts, continued
Chapter 9
Standardized Test Prep
Understanding Concepts, continued
4. The nuclei of atoms are made of protons and neutrons. Every atomic nucleus larger than that of hydrogen has at least two positively charged protons. Why do the nuclei remain intact instead of being broken apart by the repulsion of their electric charges?
Answer: The nuclear force that holds nucleons together in the nucleus is stronger than the electrical repulsion that pushes them apart.

61. Chapter 9 Reading Skills
Standardized Test Prep
Reading Skills
Radioactive isotopes are often used as “tracers” to follow the path of an element through a chemical reaction. For example, using radiotracers, chemists have determined that the oxygen atoms in O2 that are produced by a green plant during photosynthesis come from the oxygen in water and not the oxygen in carbon dioxide.
5. How could you design an experiment to determine whether the source of the oxygen produced by photosynthesis is carbon dioxide molecules or water molecules?

62. Reading Skills, continued
Chapter 9
Standardized Test Prep
Reading Skills, continued
[See reading passage on previous slide.]
5. How could you design an experiment to determine whether the source of the oxygen produced by photosynthesis is carbon dioxide molecules or water molecules?
Answer: Give one group of plants water containing radioactive oxygen atoms. Give another group carbon dioxide with radioactive oxygen atoms. Trace the radioactivity of the reaction products from both groups.

63. Interpreting Graphics
Chapter 9
Standardized Test Prep
Interpreting Graphics
6. What process is represented by the illustration?
F. alpha decay
G. nuclear chain reaction
H. radioactivity
I. nuclear fusion

64. Interpreting Graphics, continued
Chapter 9
Standardized Test Prep
Interpreting Graphics, continued
6. What process is represented by the illustration?
F. alpha decay
G. nuclear chain reaction
H. radioactivity
I. nuclear fusion