Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Chapter 10 Introduction to Organic Chemistry: Alkanes 10.2 Alkanes 1

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Alkanes Alkanes are organic molecules containing primarily C–C single bonds commonly used as fuels for heaters and cooktops whose names end in ane named by using the number of carbon atoms connected in a continuous chain 2

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. IUPAC Naming of the First Ten Alkanes 3

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Condensed Structural Formulas In a condensed structural formula, each carbon atom and its attached hydrogen atoms are written as a group a subscript indicates the number of hydrogen atoms bonded to each carbon atom of butane, four carbon atoms are attached in a straight line CH 3  CH 2  CH 2  CH 3 butane 4

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Condensed Structural Formulas Alkanes are written with structural formulas that are expanded to show each bond condensed to show each carbon atom and its attached hydrogen atoms Expanded Condensed Expanded Condensed 5

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Writing Structural Formulas Carbon atoms in a chain maintain tetrahedral shape are connected in a zigzag pattern are drawn as two-dimensional can be written in several conformations 6

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Expanded, Condensed, and Skeletal Structures 7 A hexane molecule can be represented in several ways: a molecular formula a ball-and-stick model an expanded structural formula a condensed structural formula a skeletal formula

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Expanded, Condensed, and Skeletal Structures for C 4 H 10 8

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Learning Check 1. Write the expanded structural formula for the following: 2. What is its molecular formula? 3. What is its condensed structural formula? 4. What is its name? 9

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Solution 1.Write the expanded structural formula for the following: 2.What is its molecular formula? C 5 H 12 3.What is its condensed structural formula? CH 3  CH 2  CH 2  CH 2  CH 3 4.What is its name? pentane 10

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Learning Check Write the condensed structural formula for A. ethane B. heptane 11

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Solution Write the condensed structural formula for A. ethane CH 3  CH 3 B. heptane CH 3  CH 2  CH 2  CH 2  CH 2  CH 2  CH 3 12

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Cycloalkanes are cyclic alkanes have two less hydrogen atoms than the open chain are named by using the prefix cyclo before the name of the alkane chain with the same number of carbon atoms propane, C 3 H 8 cyclopropane, C 3 H 6 13

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Formulas of Cycloalkanes 14

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Learning Check 15 Give the IUPAC name for each of the following compounds: A. B.

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Solution 16 Give the IUPAC name for each of the following compounds: A. An alkane with eight continuous carbon atoms is octane. B. A cyclic molecule with five carbons is cyclopentane.

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Learning Check Name the following alkanes: A. CH 3  CH 2  CH 2  CH 3 B. C. CH 3  CH 2  CH 2  CH 2  CH 2  CH 2  CH 2  CH 3 D. 17

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Solution Name the following alkanes: A. CH 3  CH 2  CH 2  CH 3 butane B.cyclopropane C. CH 3  CH 2  CH 2  CH 2  CH 2  CH 2  CH 2  CH 3 octane D. cyclohexane 18