Chemistry 22.2 Slide 1 of 16 22.2 Unsaturated Hydrocarbons Roach traps are baited with pheromones, which roaches produce to attract mates. The structure of many pheromones is based on unsaturated hydrocarbons. You will study two types of unsaturated hydrocarbons—alkenes and alkynes. Slide 2 of 16 © Copyright Pearson Prentice Hall 22.2 Unsaturated Hydrocarbons > Alkenes Alkenes What are the structural characteristics of alkenes? Slide 3 of 16 © Copyright Pearson Prentice Hall 22.2 Unsaturated Hydrocarbons > Alkenes At least one carbon-carbon bond in an alkene is a double covalent bond. Other bonds may be single carbon-carbon bonds and carbon-hydrogen bonds. Slide 4 of 16 © Copyright Pearson Prentice Hall 22.2 Unsaturated Hydrocarbons > Alkenes • Organic compounds that contain the maximum number of hydrogen atoms per carbon atom are called saturated compounds. • Compounds that contain double or triple carbon-carbon bonds are called unsaturated compounds. Slide 5 of 16 © Copyright Pearson Prentice Hall 22.2 Unsaturated Hydrocarbons > Alkenes Alkenes are hydrocarbons that contain one or more carbon-carbon double covalent bonds. Slide 6 of 16 © Copyright Pearson Prentice Hall 22.2 Unsaturated Hydrocarbons > Alkenes Because rotation is restricted around the double bond, atoms in ethene lie in one plane. Ethene Slide 7 of 16 © Copyright Pearson Prentice Hall 22.2 Unsaturated Hydrocarbons > Alkynes Alkynes What are the structural characteristics of alkynes? Slide 8 of 16 © Copyright Pearson Prentice Hall 22.2 Unsaturated Hydrocarbons > Alkynes At least one carbon-carbon bond in an alkyne is a triple covalent bond. Other bonds may be single or double carboncarbon bonds and single carbonhydrogen bonds. Slide 9 of 16 © Copyright Pearson Prentice Hall 22.2 Unsaturated Hydrocarbons > Alkynes • Hydrocarbons that contain one or more carbon-carbon triple covalent bonds are called alkynes. • Straight-chain and branched-chain alkanes, alkenes, and alkynes are aliphatic hydrocarbons. Slide 10 of 16 © Copyright Pearson Prentice Hall 22.2 Unsaturated Hydrocarbons > Alkynes The triple bond restricts rotation in an ethyne molecule, which has a linear shape. Slide 11 of 16 © Copyright Pearson Prentice Hall 22.2 Unsaturated Hydrocarbons > Alkenes Slide 12 of 16 © Copyright Pearson Prentice Hall 22.2 Section Quiz. Assess students’ understanding of the concepts in Section 22.2. Continue to: -or- Launch: Section Quiz Slide 13 of 16 © Copyright Pearson Prentice Hall 22.2 Section Quiz. 1. Alkenes and alkynes are called unsaturated compounds because they contain a. single bonds only. b. double or triple bonds. c. oxygen atoms. d. hydrogen atoms. Slide 14 of 16 © Copyright Pearson Prentice Hall 22.2 Section Quiz. 2. What is the correct name for a compound with a C-C-C=C-C carbon skeleton? a. 3-pentyne b. 2-pentene c. 3-pentene d. 4-pentene Slide 15 of 16 © Copyright Pearson Prentice Hall 22.2 Section Quiz. 3. Which of the following substances is an alkyne? a. C6H12 b. C2H4 c. C2H2 d. C4H8 Slide 16 of 16 © Copyright Pearson Prentice Hall END OF SHOW