Science, Tech, Math › Science Lone Pair Definition in Chemistry Print A lone pair is a pair of unbound outer shell electrons. Science Photo Library - MEHAU KULYK, 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. 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. Learn about our Editorial Process Updated on January 09, 2019 A lone pair is an electron pair in the outermost shell of an atom that is not shared or bonded to another atom. It is also called a non-bonding pair. One way to identify a lone pair is to draw a Lewis structure. The number of lone pair electrons added to the number of bonding electrons equals the number of valence electrons of an atom. The lone pair concept is important to valence shell electron pair repulsion (VSEPR) theory, as it helps to explain the geometry of molecules. Read More Nonbonding Electron Definition By Anne Marie Helmenstine, Ph.D. Sources Albright, T. A.; Burdett, J. K.; Whangbo, M.-H. (1985). Orbital Interactions in Chemistry. New York: Wiley. p. 102. ISBN 0471873934. Ansyln, E. V.; Dougherty, D. A. (2006). Modern Physical Organic Chemistry. Sausalito, CA: University Science Books. p. 41. ISBN 978-1-891389-31-3. Kumar, Anmol; Gadre, Shridhar R.; Mohan, Neetha; Suresh, Cherumuttathu H. (2014-01-06). "Lone Pairs: An Electrostatic Viewpoint". The Journal of Physical Chemistry A. 118 (2): 526–532. doi:10.1021/jp4117003 Cite this Article Format mla apa chicago Your Citation Helmenstine, Anne Marie, Ph.D. "Lone Pair Definition in Chemistry." ThoughtCo, Aug. 25, 2020, thoughtco.com/definition-of-lone-pair-605314. Helmenstine, Anne Marie, Ph.D. (2020, August 25). Lone Pair Definition in Chemistry. Retrieved from https://www.thoughtco.com/definition-of-lone-pair-605314 Helmenstine, Anne Marie, Ph.D. "Lone Pair Definition in Chemistry." ThoughtCo. https://www.thoughtco.com/definition-of-lone-pair-605314 (accessed April 26, 2024). copy citation