Science, Tech, Math › Science Lewis Acid-Base Reaction Definition Share Flipboard Email Print Spencer Grant/Getty Images 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 March 06, 2017 A Lewis acid-base reaction is a chemical reaction that forms at least one covalent bond between an electron pair donor (Lewis base) and an electron pair acceptor (Lewis acid). The general form of a Lewis acid-base reaction is: A+ + B- → A-B where A+ is an electron acceptor or Lewis acid, B- is an electron donor or Lewis base, and A-B is a coordinate covalent compound. Significance of Lewis Acid-Base Reactions Most of the time, chemists apply the Brønsted acid-base theory (Brønsted-Lowry) in which acids act as proton donors and bases are proton acceptors. While this works well for many chemical reactions, it doesn't always work, particularly when applied to reactions involving gases and solids. The Lewis theory focuses on electrons rather than proton transfer, allowing for prediction of many more acid-base reactions. Example Lewis Acid-Base Reaction While Brønsted theory cannot explain the formation of complex ions with a central metal ion, Lewis acid-base theory sees the metal as the Lewis Acid and the ligand of the coordination compound as a Lewis Base. Al3+ + 6H2O ⇌ [Al(H2O)6]3+ The aluminum metal ion has an unfilled valence shell, so it acts as an electron acceptor or Lewis acid. Water has lone pair electrons, so it can donate electrons to serve as the anion or Lewis base.