Science, Tech, Math › Science Functional Groups Definition and Examples Chemistry Glossary Definition of Functional Groups Share Flipboard Email Print Benzyl acetate has an ester group (red). Wikimedia Commons/Public Domain Science Chemistry Chemical Laws Basics Molecules Periodic Table Projects & Experiments Scientific Method Biochemistry Physical Chemistry Medical Chemistry Chemistry In Everyday Life Famous Chemists Activities for Kids Abbreviations & Acronyms Biology Physics Geology Astronomy Weather & Climate By Anne Marie Helmenstine, Ph.D. Chemistry Expert Ph.D., Biomedical Sciences, University of Tennessee at Knoxville B.A., Physics and Mathematics, Hastings College Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels. our editorial process Facebook Facebook Twitter Twitter Anne Marie Helmenstine, Ph.D. Updated July 03, 2019 Functional Groups Definition A functional group or moiety is a specific group of atoms within a molecule that is responsible for characteristic chemical reactions of that molecule. No matter what size a molecule is, a functional group participates in chemical reactions in a predictable manner. Functional groups link to the rest of the molecule via covalent bonds. The group may be neutral or charged. Functional Group Examples: Examples of common functional groups include alcohol (-OH), aldehyde (-COH), and nitrile (-CN). Nomenclature The naming convention for moieties describes whether it is saturated or unsaturated and whether it contains single, double, or triple bonds. Class Formula Suffix Example Single bond R• -yl Methyl group, Methyl radical Double bond R: -ylidene Methylidene Triple bond R⫶ -ylidyne Methylidyne Carboxylic acyl radical R−C(=O)• -oyl Acetyl Source Brown, Theodore (2002). Chemistry : The Central Science. Upper Saddle River, NJ: Prentice Hall. p. 1001. ISBN 0130669970. Review of Organic Functional Groups What Is a Sol? What Is a Moiety in Chemistry? Defining an Enzyme Structure and Function What Is the Carboxyl Group in Chemistry? Review the Functional Groups in Organic Chemistry What Are Amphipathic Molecules? What Is a Fat? Chemistry Vocabulary Terms You Should Know What Is a Carbonyl Group in Chemistry? Monosaccharide Definition and Functions Learn What an Acyl Group Is in Chemistry Find out What a Trans Isomer Is What Is a Decomposition or Analysis Reaction in Chemistry? Get Examples of Pure Substances What Is an Alkoxide?