Science, Tech, Math › Science Octet Rule Definition in Chemistry Chemistry Glossary Definition of Octet Rule Print This is the Lewis structure of carbon dioxide, illustrating the octet rule. Ben Mills 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 November 04, 2019 The octet rule in chemistry is the principle that bonded atoms share their eight outer electrons. This gives the atom a valence shell resembling that of a noble gas. The octet rule is a "rule" that is sometimes broken. However, it applies to carbon, nitrogen, oxygen, the halogens, and most metals, especially the alkali metals and alkaline earths. Read More The Octet Rule Explanation in Chemistry By Anne Marie Helmenstine, Ph.D. A Lewis electron dot diagram may be drawn to illustrate the octet rule. In such a structure, electrons shared in a covalent bond between two atoms are counted twice (once for each atom). Other electrons are counted once. Sources Abegg, R. (1904). "Die Valenz und das periodische System. Versuch einer Theorie der Molekularverbindungen (Valency and the periodic system – Attempt at a theory of molecular compounds)". Zeitschrift für anorganische Chemie. 39 (1): 330–380. doi:10.1002/zaac.19040390125 Langmuir, Irving (1919). "The Arrangement of Electrons in Atoms and Molecules". Journal of the American Chemical Society. 41 (6): 868–934. doi:10.1021/ja02227a002 Lewis, Gilbert N. (1916). "The Atom and the Molecule". Journal of the American Chemical Society. 38 (4): 762–785. doi:10.1021/ja02261a002 Cite this Article Format mla apa chicago Your Citation Helmenstine, Anne Marie, Ph.D. "Octet Rule Definition in Chemistry." ThoughtCo, Aug. 27, 2020, thoughtco.com/definition-of-octet-rule-604588. Helmenstine, Anne Marie, Ph.D. (2020, August 27). Octet Rule Definition in Chemistry. Retrieved from https://www.thoughtco.com/definition-of-octet-rule-604588 Helmenstine, Anne Marie, Ph.D. "Octet Rule Definition in Chemistry." ThoughtCo. https://www.thoughtco.com/definition-of-octet-rule-604588 (accessed April 19, 2024). copy citation