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Resources Bellringers Chapter Presentation Transparencies Standardized Test Prep Image and Math Focus Bank CNN Videos Visual Concepts

Atomic Energy Chapter 16 Table of Contents Section 1 Radioactivity Section 2 Energy from the Nucleus

Section1 Radioactivity Chapter 16 Bellringer In your science journalwrite a few sentences about the term nuclear radiation. Include what you know about nuclear radiation, any benefits, and any dangers you can think of. For example, when is radiation used to help people? When is radiation harmful?

Section1 Radioactivity Chapter 16 Objectives • Describe how radioactivity was discovered. • Compare alpha, beta, and gamma decay. • Describe the penetrating power of the three kinds of nuclear radiation. • Calculateages of objects using half-life. • Identify uses of radioactive materials.

Section1 Radioactivity Chapter 16 Discovering Radioactivity • An Unexpected ResultHenri Becquerel discovered that radium gave off a form of radiation. • Naming the UnexpectedMarie Curie, a scientist working with Becquerel, named the process by which some nuclei give off nuclear radiation. She named the process radioactivity, which is also called radioactive decay.

Section1 Radioactivity Chapter 16 Kinds of Radioactive Decay • Alpha DecayThe release of an alpha particle from a nucleus is called alpha decay. An alpha particle is made up of two protons and two neutrons. • Conservation in DecayIn radioactive decay, the mass number is conserved, and the charge is conserved. • Beta DecayThe release of a beta particle from a nucleus is called beta decay. A beta particle can be an electron or a positron.

Section1 Radioactivity Chapter 16

Section1 Radioactivity Chapter 16 Kinds of Radioactive Decay, continued • Two Types of Beta DecayA carbon-14 nucleus undergoes beta decay. During this kind of decay, a neutron breaks into a proton and an electron. Not all isotopes of an element decay in the same way. A carbon-11 nucleus undergoes beta decay when a proton breaks into a positron and a neutron. • Gamma DecayEnergy is also given off during alpha decay and beta decay. Some of this energy is in the form of light that has very high energy called gamma rays.

Section1 Radioactivity Chapter 16 The Penetrating Power of Radiation • Effects of Radiation on MatterAtoms that are hit by nuclear radiation can give up electrons. Chemical bonds between atoms can break when hit by nuclear radiation. • Damage to Living MatterWhen an organism absorbs radiation, its cells can be damaged. A single large exposure to radiation can lead to radiation sickness.

Section1 Radioactivity Chapter 16 The Penetrating Power of Radiation, continued • Damage to Nonliving MatterRadiation can also damage nonliving matter. When metal atoms lose electrons, the metal is weakened. • Damage at Different DepthsGamma rays go through matter easily. They can cause damage deep within matter. The penetrating powers of different forms of radiation can be seen on the next slide.

Section1 Radioactivity Chapter 16 Finding a Date by Decay • Carbon-14—It’s in You!During an organism’s life, the percentage of carbon-14 in the organism stays about the same. But when an organism dies, over time the level of carbon-14 in the remains drops because of radioactive decay. • A Steady Rate of DecayA half-life is the amount of time it takes one-half of the nuclei of a radioactive isotope to decay. The next slide models this process.

Section1 Radioactivity Chapter 16 Finding a Date by Decay, continued • Determining AgeCarbon-14 can be used to find the age of objects up to 50,000 years old. To find the age of older things, other elements must be used.

Section1 Radioactivity Chapter 16 Uses of Radioactivity • Radioactivity in HealthcareDoctors use tracers to help diagnose medical problems. Radioactive tracers that have short half-lives are fed to or injected into a patient. Then, a detector is used to follow the tracer as it moves through the body. • Radioactivity in IndustryRadioactive isotopes can also help detect defects in structures. Some space probes have been powered by radioactive materials.

Section1 Radioactivity Chapter 16 Radioactive Tracer Click below to watch the Visual Concept. You may stop the video at any time by pressing the Esc key. Visual Concept

Section2 Energy from the Nucleus Chapter 16 Bellringer Define each of the following terms in your own words in your science journal: fission fusion Are the terms opposites, or are they similar? How is energy involved in each? Discuss your ideas with the group.

Section2 Energy from the Nucleus Chapter 16 Objectives • Describe nuclear fission. • Identify advantages and disadvantages of fission. • Describe nuclear fusion. • Identify advantages and disadvantages of fusion.

Section2 Energy from the Nucleus Chapter 16 Nuclear Fission • Nuclear Fissionis the process by which a large nucleus splits into two small nuclei and releases energy. • Energy from Matter The nuclear fission of the uranium nuclei in one fuel pellet releases as much energy as the chemical change of burning about 1,000 kg of coal. The nuclear fission of uranium-235 is shown on the next slide.

Section2 Energy from the Nucleus Chapter 16

Section2 Energy from the Nucleus Chapter 16 Nuclear Fission, continued • Nuclear Chain ReactionsA nuclear chain reaction is a continuous series of nuclear fission reactions.

Section2 Energy from the Nucleus Chapter 16 Nuclear Fission, continued • Energy from a Chain ReactionNuclear power plants use controlled chain reactions. The energy released from the nuclei in the uranium fuel within the nuclear power plants is used to generate electrical energy. The nextslide shows how a nuclear power plant works.

Section2 Energy from the Nucleus Chapter 16

Section2 Energy from the Nucleus Chapter 16 Advantages and Disadvantages of Fission • AccidentsA concern that many people have about nuclear power is the risk of an accident. • What Waste!Controlled fission has been carried out for only about 50 years. But the waste will give off high levels of radiation for thousands of years. • Nuclear Versus Fossil FuelNuclear power plants cost more to build than power plants that use fossil fuels, but often cost less to run than plants that use fossil fuels because less fuel is needed.

Section2 Energy from the Nucleus Chapter 16 Nuclear Fusion • What Is Nuclear Fusion?In nuclear fusion, two or more nuclei that have small masses combine, or fuse, to form a larger nucleus. • Plasma NeededIn order for fusion to happen, the repulsion between positively charged nuclei must be overcome. Very high temperatures are needed—more than 100,000,000 °C! At these high temperatures, matter is a plasma.

Section2 Energy from the Nucleus Chapter 16 Advantages and Disadvantages of Fusion • Less Accident ProneThe concern about an accident such as the one at Chernobyl is much lower for fusion reactors. • Oceans of FuelScientists studying fusion use hydrogen-2 and hydrogen-3 in their work. Hydrogen-1 is much more common than these isotopes. But there is enough of them in Earth’s waters to provide fuel for millions of years.

Section2 Energy from the Nucleus Chapter 16 Advantages and Disadvantages of Fusion, continued • Less WasteThe products of fusion reactions are not radioactive. So, fusion is a “cleaner” source of energy than fission is.

Atomic Energy Chapter 16 Concept Map Use the terms below to complete the concept map on the next slide.

Concept Map Chapter 16

End of Chapter 16 Show

Standardized Test Preparation Chapter 16 Reading Read each of the passages. Then, answer the questions that follow each passage.

Standardized Test Preparation Chapter 16 Passage 1Have you noticed that your forks, knives, and spoons don’t tarnish easily? Most metal utensils are made of stainless steel. Because it doesn’t tarnish, stainless steel is also used in nuclear reactors. Some scientists study radiation’s effects on metals and other substances. An important focus of their studies is radiation’s effect on the structure of stainless steel. The damage to stainless steel is caused mainly by neutron and heavy ion radiation inside nuclear reactors. Continued on the next slide

Standardized Test Preparation Chapter 16 Passage 1, continuedThe radiation causes stress in the metal. The stress leads to corrosion and finally to cracking. Clearly, this feature is not desirable in parts of a nuclear reactor! Scientists hope that by studying the way radiation affects the atoms of metals, they can find a way to use the incoming radiation to make the surface stronger instead of weaker.

Standardized Test Preparation Chapter 16 1.Which of the following happens last as stainless steel is damaged in a nuclear reactor? AThe steel corrodes. BThe steel is exposed to radiation. CThe steel cracks. DThe steel is stressed.

Standardized Test Preparation Chapter 16 1.Which of the following happens last as stainless steel is damaged in a nuclear reactor? AThe steel corrodes. BThe steel is exposed to radiation. C The steel cracks. DThe steel is stressed.

Standardized Test Preparation Chapter 16 2. Which of the following is a goal of the scientists? Fto use radiation to strengthen stainless steel Gto keep stainless steel from tarnishing Hto keep spoons and forks from cracking Ito prevent stainless steel from absorbing radiation

Standardized Test Preparation Chapter 16 2. Which of the following is a goal of the scientists? F to use radiation to strengthen stainless steel Gto keep stainless steel from tarnishing Hto keep spoons and forks from cracking Ito prevent stainless steel from absorbing radiation

Standardized Test Preparation Chapter 16 3. Why is stainless steel a good metal to use in a nuclear reactor? AIt is made stronger by radiation. BIt does not tarnish easily. CIt cracks under stress. DIt is not affected by radiation.

Standardized Test Preparation Chapter 16 3. Why is stainless steel a good metal to use in a nuclear reactor? AIt is made stronger by radiation. B It does not tarnish easily. CIt cracks under stress. DIt is not affected by radiation.

Standardized Test Preparation Chapter 16 Passage 2A space probe takes about 7 years to reach Saturn. What could supply energy for the cameras and equipment after that time in space? The answer is the radioactive element plutonium! The nuclei (singular, nucleus) of plutonium atoms are radioactive, so the nuclei are unstable. They become stable by giving off radiation in the form of particles and rays. This process heats the materials surrounding the plutonium, and the thermal energy of the materials is converted into electrical energy by a radioisotope thermoelectric generator (RTG). Continued on the next slide

Standardized Test Preparation Chapter 16 Passage 2, continuedSpacecraft such as Voyager, Galileo, and Ulysses depended on RTGs for electrical energy. Because an RTG can generate electrical energy for 10 or more years by using one sample of plutonium, an RTG provides energy longer than any battery can. In fact, the RTGs on Voyager were still providing energy after 20 years!

Standardized Test Preparation Chapter 16 1. Plutonium in an RTG can be expected to provide energy for how long? Amuch less than 7 years Babout 7 years C10 years or more D20 years

Standardized Test Preparation Chapter 16 1. Plutonium in an RTG can be expected to provide energy for how long? Amuch less than 7 years Babout 7 years C 10 years or more D20 years

Standardized Test Preparation Chapter 16 2. Which of the following terms has the most similar meaning to the term radioactive? Fthermoelectric Gplutonium Hradiation Iunstable

Standardized Test Preparation Chapter 16 3. What is the final form of energy provided by RTGs? Athermal Belectrical Cparticles and rays Dnuclear

Standardized Test Preparation Chapter 16 Interpreting Graphics The table below shows the half-lives of some radioactive isotopes. Use the table below to answer the questions that follow.

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