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Section 2Nuclear Changes Section 2: Nuclear Fission and Fusion Preview Key Ideas Bellringer Nuclear Forces Nuclear Fission Chain Reaction Nuclear Fusion.

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Presentation on theme: "Section 2Nuclear Changes Section 2: Nuclear Fission and Fusion Preview Key Ideas Bellringer Nuclear Forces Nuclear Fission Chain Reaction Nuclear Fusion."— Presentation transcript:

1 Section 2Nuclear Changes Section 2: Nuclear Fission and Fusion Preview Key Ideas Bellringer Nuclear Forces Nuclear Fission Chain Reaction Nuclear Fusion

2 Section 2Nuclear Changes Key Ideas What holds the nuclei of atoms together? What is released when the nucleus of a heavy atom is split? What happens when the nuclei of small atoms are joined?

3 Section 2Nuclear Changes 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 on the next slide, and answer the following questions.

4 Section 2Nuclear Changes Bellringer, continued

5 Section 2Nuclear Changes 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 most likely would be useful for this type of research? Explain your answer.

6 Section 2Nuclear Changes SPS3.b Differentiate between fission and fusion.

7 Section 2Nuclear Changes EQ: How do fission and fusion differ?

8 Section 2Nuclear Changes Nuclear Forces What holds the nuclei of atoms together?

9 Section 2Nuclear Changes Nuclear Forces The stability of a nucleus depends on the nuclear forces that act between protons and neutorons and hold the nucleus together.

10 Section 2Nuclear Changes Nuclear Forces, continued strong nuclear force: causes protons and neutrons in the nucleus to attract each other

11 Section 2Nuclear Changes Nuclear Forces, continued Neutrons contribute to nuclear stability.

12 Section 2Nuclear Changes Nuclear Forces, continued Nuclei with more than 83 protons are always unstable.

13 Section 2Nuclear Changes Nuclear Forces, continued

14 Section 2Nuclear Changes Nuclear Fission What is released when the nucleus of a heavy atom is split?

15 Section 2Nuclear Changes Nuclear Fission fission: the process by which a nucleus splits into two or more fragments and releases neutrons and energy

16 Section 2Nuclear Changes Nuclear Fission, continued Fission of Uranium-235:

17 Section 2Nuclear Changes Nuclear Fission, continued According to Einsteins equation, E = mc 2, mass is converted to energy in a fission reaction.

18 Section 2Nuclear Changes Nuclear Fission, continued –mass defect: the difference in the total measured mass of a nucleus and the sum of the individual masses of the neutrons and protons that make up the nucleus

19 Section 2Nuclear Changes Nuclear Fission, continued The mass defect is the amount of mass that has been changed to energy.

20 Section 2Nuclear Changes Nuclear Fission, continued –nuclear chain reaction: a continuous series of nuclear fission reactions caused by the release of electrons

21 Section 2Nuclear Changes Nuclear Fission, continued –critical mass: the minimum mass of a fissionable isotope that provides the number of neutrons needed to sustain a chain reaction

22 Section 2Nuclear Changes Chain Reaction

23 Section 2Nuclear Changes Nuclear Fusion What happens when the nuclei of small atoms are joined?

24 Section 2Nuclear Changes Nuclear Fusion fusion: the process in which light nuclei combine at extremely high temperatures, forming heavier nuclei and releasing energy

25 Section 2Nuclear Changes Nuclear Fusion, continued In stars, energy is produced when hydrogen nuclei combine.

26 Section 2Nuclear Changes Nuclear Fusion, continued A large amount of energy and a very high temperature is needed to start a fusion reaction.

27 Section 2Nuclear Changes Nuclear Fusion, continued Four hydrogen atoms combine to make a helium atom and high- energy gamma rays in a three- step process.

28 Section 2Nuclear Changes Nuclear Fusion, continued Fusion reactions are not practical now because of the difficulty of containing such a high temperature reaction.

29 Section 2Nuclear Changes Nuclear Fusion, continued Two big advantages of fusion are they produce more energy than fission and they dont make hazardous wastes.

30 Section 2Nuclear Changes Nuclear Fusion, continued


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