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| Understanding the concepts
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| 1.a.
| Characterize the differences between ionic bonding, covalent bonding, and polar covalent bonding. Why do atoms combine to form covalent bonds? To check your answer, view the Bond Orbital Formation in H2 Understanding Concepts on the CD.
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| b.
| The Example in the Understanding Concepts, above, examines energy changes when two separate H atoms are brought closer together. Click "Play" to move the H atoms closer together. What point on the plot represents the bond length distance in H2? Why does the energy increase when H atoms are moved closer together than the bond length distance?
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| 2.a.
| Define electronegativity. How is the difference in electronegativity between two atoms related to the type of bond that will form? On the Web site, review the Table showing the Relationship Between Electronegativity and Bond Type to check your answer.
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| b.
| What is the periodic trend in electronegativity values? Review Figure 11.3 in the text, which lists electronegativity values. Where does hydrogen fit into the trend? This is important to know because many covalent bonds involve hydrogen. For practice working with electronegativity values, do Problems 11.12, 11.14, 11.16, 11.18, 11.20, 11.24, and 11.26 in the text. |
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| 3.a.
| When a metal reacts with a nonmetal, an ionic compound forms. What type of ions do the metals form? the nonmetals? How do you predict the charges of the ions from a periodic table? Why do the various representative groups form these charges? To help you answer these questions, open the following Tables on the Web site: Formation of Ions by Metals and Nonmetals and Common Ions with Noble Gas Configurations in Ionic Compounds. For some good exercises on ions and ionic compounds, do Problems 11.34, 11.38, and 11.40 in the text.
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| b.
| When a cation forms, how does the size of the ion compare to the parent atom? What about anions? For exercises on ion sizes, do Problems 11.46 and 11.48 in the text. |
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| 4.a.
| To predict bond angles and molecular structure for various compounds, you first must have a correct Lewis structure. To test your ability to draw Lewis structures, open The VSEPR Theory of Molecular Structure Understanding Concepts on the CD and skip directly to the Exercises. For each molecule or ion, draw on your own the correct Lewis structure. To check your work, click Hint: Examine Lewis Structure. Ignore XeF2 in the Exercises. |
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| b.
| The Lewis structures in the Hints are incorrect for CO2, NO2-, O3, and SO2-. What is wrong with the answers? NO2-, O3, and SO2 all exhibit resonance. What is resonance and how many resonance structures can be drawn for these three species? How many resonance structures can be drawn for CO32-? for SO3? |
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| c.
| There are exceptions to the octet rule. Explain why BH3 and BeH2 are exceptions. Why must NO and NO2 molecules violate the octet rule for at least one atom in the compound? |
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| 5.a.
| The VSEPR model is used to predict the molecular structures of various compounds. What is the main idea of the VSEPR model? When two pairs of electrons are present around a central atom, what is the arrangement of the electrons? What about when three or four pairs of electrons are present around a central atom? |
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| b.
| The molecular structure of a molecule is based on the positions of the atoms. When is the molecular structure of a compound not the same as the electron pair arrangement? View the Table on Arrangements of Electron Pairs on the Web site to help you answer the questions above. |
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| c.
| Open the VSEPR Theory of Molecular Structure Understanding Concepts on the CD and read the Introduction and Example to review how to apply the VSEPR model to predict molecular structures of molecules/ions. The table at the end of the example offers a good review of the possible molecular structures. Review the table and make sure that you can list approximate bond angles present for each molecular structure. |
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| d.
| Go to the Exercises in the Understanding Concepts, above, and predict the molecular structure (shape) for every example available (except for XeF2). This is an excellent review exercise on molecular structures, so be thorough. While going through each molecule/ion, also predict the approximate bond angles. To see a representation of a particular molecule/ion, click Hint: Examine Shape. |
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| 6.
| Open Key Words on the CD and test your ability to define important terms presented in Chapter 11. |
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| 7.
| Test you understanding of Chapter 11 material by taking the ACE quizzes on the Web site. |
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