22.1 HYDROCARBONS Section Review Objectives Describe the relationship between number of valence electrons and bonding in carbon Define and describe alkanes Relate the polarity of hydrocarbons to their solubility Vocabulary hydrocarbons alkanes straight-chain alkanes Part A Completion homologous series condensed structural formulas substituent alkyl group branched-chain alkane Use this completion exercise to check your understanding of the concepts and terms that are introduced in this section. Each blank can be completed with a term, short phrase, or number. The branch of chemistry that deals with 1 compounds 1. is called 2 chemistry. Organic compounds that contain 2. only carbon and hydrogen are 3. Carbon always forms 3. 4 covalent bonds. 4. Alkanes contain only carbon-carbon 5 bonds. The 5. carbons can be arranged in a 6 chain or in a chain that 6. has 7. A hydrocarbon substituent is called an 8 7. group. The first step in naming branched-chain alkanes is to find 8. the 9 chain of carbons in the molecule. This chain is the 9. 10 structure. 10. Part B True-False Classify each of these statements as always true, AT; sometimes true, ST; or never true, NT. 11. Because a carbon atom contains 6 valence electrons, it forms 3 covalent bonds. Chapter 22 Hydrocarbon Compounds 567
12. Straight-chain alkanes contain 10 carbon atoms. 13. A substituent can take the place of a hydrogen atom on a parent hydrocarbon molecule. 14. Hydrocarbon structural formulas are numbered from right to left. 15. When naming branched-chain hydrocarbons, the names of the substituent alkyl groups are listed in alphabetical order. Part C Matching Match each description in Column B to the correct term in Column A. Column A Column B 16. hydrocarbons 17. alkanes 18. straight-chain alkanes 19. substituent 20. alkyl group a. hydrocarbons that contain only single covalent bonds b. a hydrocarbon substituent c. alkanes that contain one or more alkyl substituents d. organic compounds that contain only carbon and hydrogen e. alkanes that contain any number of carbons one after another in a chain 21. branched-chain alkanes Part D Questions and Problems Answer the following in the space provided. 22. Name this compound, using the IUPAC system. CH 3 CH 3 2 C 2 CH 2 2 CH 3 CH 3 23. a. What is the total number of single bonds in a molecule of pentane, C 5 H 12? b. What is the total number of single bonds in a molecule of 2,2-dimethylpropane? f. atom or group of atoms that take the place of a hydrogen atom in a hydrocarbon molecule 24. Write the structural formula for 3-ethyl-2,2,5-trimethyloctane. 568 Core Teaching Resources
22.2 UNSATURATED HYDROCARBONS Section Review Objectives Describe the difference between unsaturated and saturated hydrocarbons Distinguish the structures of alkenes and alkynes Vocabulary saturated compounds unsaturated compounds alkenes alkynes aliphatic hydrocarbons Part A Completion Use this completion exercise to check your understanding of the concepts and terms that are introduced in this section. Each blank can be completed with a term, short phrase, or number. Alkenes are 1 hydrocarbons. That is, they contain one 1. or more carbon-carbon 2 bonds. Alkynes are also 2. unsaturated compounds. They contain one or more carbon- 3. carbon 3 bonds. Rotation is restricted about the multiple 4. bonds of alkenes and alkynes. 5. Alkenes are named by finding the 4 chain in the 6. molecule that contains a 5 bond. The root name of the 7. corresponding 6 is used, plus the ending 7. Atoms 8. are numbered so that the carbon atoms of the 8 have the 9. lowest possible numbers. Alkynes are named in the same way, except that the ending 9 is added to the alkane root. Part B True-False Classify each of these statements as always true, AT; sometimes true, ST; or never true, NT. 10. An alkane with one or more alkyl groups is called an alkyne. 11. Hydrocarbons are saturated. Chapter 22 Hydrocarbon Compounds 569
12. Parent alkene chains are numbered so that the carbons of the double bond have the lowest possible numbers. 13. Unsaturated hydrocarbons contain double bonds. Part C Matching Match each description in Column B to the correct term in Column A. Column A Column B 14. unsaturated compounds 15. saturated compounds 16. alkenes 17. alkynes a. contain at least one carbon-carbon double bond b. contain at least one carbon-carbon triple bond c. organic compounds that contain double or triple carbon-carbon bonds d. hydrocarbons that contain the maximum number of hydrogen atoms per carbon atom Part D Questions and Problems Answer the following in the space provided. 18. Name this compound using the IUPAC system. CH 3 2 CH 2 CH 3 CH 2 2 C 3 CH 2 CH 3 19. Name this compound, using the IUPAC system. CH 3 2 CH 2 CH 2 CH 2 CH 2 CH 2 2 CH 2 2 CH 2 2 CH 3 CH 3 CH 3 CH 3 CH 3 20. Name the following compound, using the IUPAC system. H H 2 C 2 H H H 2 C 2 H H H H H 2 C 22 C 22 C 2 C 3 C 2 H H H H 21. Draw the structural formula for the following compound. 7-ethyl-2,4,9-trimethyl-5-decyne. 570 Core Teaching Resources
22.3 ISOMERS Section Review Objectives Explain why structural isomers have different properties Describe the conditions under which geometric isomers are possible Identify optical isomers Vocabulary isomers structural isomers stereoisomers geometric isomers trans configuration cis configuration asymmetric carbon optical isomers Part A Completion Use this completion exercise to check your understanding of the concepts and terms that are introduced in this section. Each blank can be completed with a term, short phrase, or number. Isomers have the same 1 formula but different 1. molecular 2. For example, 2 methylpropane is a structural 2. isomer of 3. Isomers are different compounds with different 3. 4. 4. 5 isomers differ in the orientation of groups around 5. a double bond. The two possible double-bond configurations are 6. the 6 configuration and the 7 configuration. 7. Geometric isomers are one type of 8. The other type 8. contains a carbon atom with four different groups attached, 9. which is called an 9 carbon. Isomers with an asymmetric 10. carbon are 10 isomers. 11. Models of optical isomers are like 11 images, which 12. cannot be 12. Chapter 22 Hydrocarbon Compounds 571
Part B True-False Classify each of these statements as always true, AT; sometimes true, ST; or never true, NT. 13. Structural isomers are compounds with identical molecular structures. 14. Compounds containing double bonds have cis, trans isomers. 15. Isomers with the atoms joined in the same order are structural isomers. 16. A carbon with four different groups attached is an asymmetric carbon. Part C Matching Match each description in Column B to the correct term in Column A. Column A Column B 17. isomers 18. structural isomers 19. stereoisomers 20. geometric isomers 21. trans configuration 22. cis configuration 23. asymmetric carbon 24. optical isomers a. a carbon with four different groups attached b. configuration with substituted groups on the same side of the double bond c. isomers that differ in the concentration of groups around a double bond d. molecules in which the atoms are joined in the same order, but the arrangements of the atoms in space are different e. compounds that have the same molecular formula, but the atoms are joined in a different order f. configuration with substituted groups on opposite sides of the double bond g. pairs of molecules that differ only in the way four different groups are arranged around a central carbon atom h. compounds that have the same molecular formula but different molecular structures 572 Core Teaching Resources
Part D Problems Answer the following in the space provided. 25. Draw three structural isomers of pentane. 26. Identify the asymmetric carbon in this compound. H 5 4 3 2 1 CH 3 2 CH 2 2 CH 2 2 C 2 CH 3 F 27. Draw the cis and trans isomers for 3-hexene. Chapter 22 Hydrocarbon Compounds 573
22.4 HYDROCARBON RINGS Section Review Objectives Identify cyclic ring structures Describe bonding in benzene Vocabulary cyclic hydrocarbons aromatic compound Part A Completion Use this completion exercise to check your understanding of the concepts and terms that are introduced in this section. Each blank can be completed with a term, short phrase, or number. Compounds with hydrocarbon rings are called 1 1. hydrocarbons. Benzene is the simplest form of an 2 2. compound. The benzene molecule consists of 3 carbons 3. joined in a ring with a 4 atom attached to each carbon. 4. Two different structures can be written for benzene in which 5. 5 and single bonds alternate. The actual bonding in 6. benzene does not alternate between the 6 structures. 7. Many substituted benzenes have common names. 7 8. is also called toluene, while the dimethylbenzenes are known as 9. 8. 1,2 disubstitution on a benzene ring is also know as 10. 9 disubstitution, while 1,3 is known as 10, and 1,4 is 11. known as 11 disubstitution. 574 Core Teaching Resources
Part B True-False Classify each of these statements as always true, AT; sometimes true, ST; or never true, NT. 12. Aromatic compounds contain 6 carbon atoms. 13. Benzene is the simplest arene. 14. Compounds that contain rings are aromatic hydrocarbons. 15. Another name for 1,3-dimethylbenzene is m-xylene. 16. Aromatic compounds have pleasant odors. Part C Matching Match each description in Column B to the correct term in Column A. Column A Column B 17. cyclic hydrocarbons 18. resonance 19. phenyl group 20. aromatic compounds a. when two or more equally valid structures can be drawn for a molecule b. group of hydrocarbons that contain a benzene ring or a ring with bonding like that of benzene c. name given to a benzene ring when it is a substituent d. organic compounds that contain hydrocarbon rings Part D Problems Answer the following in the space provided. 21. Draw the structural formula for propylbenzene. 22. Draw the structural formula for 3-phenyl-1-butene. 23. Name the following compounds, using the IUPAC system. a. CH 2 2 CH 2 b. ^ % CH 2 CH 2 CH 2 CH 2 % ^ CH 2 2 CH 2 CH 2 CH 3 % CH 2 CH 3 Chapter 22 Hydrocarbon Compounds 575
22.5 HYDROCARBONS FROM EARTH S CRUST Section Review Objectives Identify three important fossil fuels and describe their origins Describe the composition of natural gas, petroleum, and coal Describe what happens when petroleum is refined Vocabulary cracking Part A Completion Use this completion exercise to check your understanding of the concepts and terms that are introduced in this section. Each blank can be completed with a term, short phrase, or number. The three fossil fuels are 1, petroleum, and 2. 1. The majority of natural gas, about 80 percent, is 3. 2. Most of the hydrocarbons in petroleum and natural gas are 3. 4 hydrocarbons. Petroleum is refined by 5 it into 4. fractions according to 6. 5. Coal is produced when peat, which is derived from plant 6. material, changes to 7, or brown coal. This in turn 7. becomes 8, or soft coal, then 9, or hard coal. 8. Coal is made up largely of condensed 10 compounds. 9. Part B True-False Classify each of these statements as always true, AT; sometimes true, ST; or never true, NT. 11. Carbon monoxide is the product of the complete combustion of a hydrocarbon. 10. 12. Natural gas is composed mostly of aromatic hydrocarbons. 576 Core Teaching Resources
13. Among the various types of coal, anthracite has the highest carbon content. 14. Hydrocarbons produce carbon monoxide when burned. Part C Matching Match each description in Column B to the correct term in Column A. Column A 15. cracking 16. petroleum 17. distillation 18. lignite 19. anthracite Column B a. hard coal, which is high in carbon content b. process by which hydrocarbons are broken down into smaller molecules c. brown coal, consisting of about 50 percent carbon d. fossil fuel containing straight- and branched-chain alkanes e. process by which petroleum is separated into fractions Part D Problems Answer the following in the space provided. 20. Balance the equation for the incomplete combustion of pentane to form CO and H 2 O. 21. Balance the following equation. C 6 H 6 O 2 CO 2 H 2 O Chapter 22 Hydrocarbon Compounds 577