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Chapter 6 Lecture Basic Chemistry Fourth Edition Chapter 6 Ionic and Molecular Compounds 6.7 Names and Formulas of Alkanes Learning Goal Write the IUPAC name and draw the condensed structural formula for an alkane. © 2014 Pearson Education, Inc. Alkanes Alkanes • are a class of hydrocarbons in which all atoms are connected by single bonds • are commonly used as fuels • contain carbons connected in a row or a continuous chain © 2014 Pearson Education, Inc. Naming Alkanes The IUPAC (International Union of Pure and Applied Chemistry) system is used for naming alkanes. Alkanes with five or more carbons in a chain are named using prefixes and the ending ane. • Pentane is a five-carbon chain. • Octane is an eight-carbon chain. © 2014 Pearson Education, Inc. Naming Alkanes © 2014 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 is used to represent the number of hydrogen atoms attached to each carbon. © 2014 Pearson Education, Inc. Models for Larger Alkanes Alkanes with more than three carbons are written in a zigzag pattern instead of a straight line. We can use different models to represent these molecules. © 2014 Pearson Education, Inc. Learning Check A. What is the condensed formula for H H H H H HCCCCCH H H H H H B. What is its molecular formula? C. What is its name? © 2014 Pearson Education, Inc. Solution A. H H H H H HCCCCCH H H H H H CH3CH2CH2CH2CH3 B. What is its molecular formula? C5H12 C. What is its name? pentane © 2014 Pearson Education, Inc. Learning Check Draw the condensed structural formula for heptane. © 2014 Pearson Education, Inc. Solution Draw the condensed structural formula for heptane. The prefix in heptane indicates that the condensed structural formula contains seven carbon atoms. Heptane CH3CH2CH2CH2CH2CH2CH3 © 2014 Pearson Education, Inc. Properties of Alkanes Alkanes are nonpolar and less dense than water. Alkanes with • 1-4 carbon atoms are gases • 5-8 carbon atoms are liquids at room temperature • 9-17 carbon atoms are liquids such as kerosene and jet fuel The solid alkanes that • 18 or more carbon atoms are make up waxy coatings on fruits and vegetables waxy solids help to retain moisture, © 2014 Pearson Education, Inc. inhibit mold, and enhance appearance. Chemistry Link to Industry Crude oil, or petroleum, contains a wide variety of hydrocarbons. At a refinery, the components in crude oil are separated by fractional distillation, a process that separates groups of hydrocarbons by continually heating the mixture to higher temperatures. © 2014 Pearson Education, Inc. Chemistry Link to Industry Alkanes with longer carbon chains require higher temperatures to reach their boiling point and form gases. © 2014 Pearson Education, Inc. Concept Map, Ionic and Molecular Compounds © 2014 Pearson Education, Inc.