Science, Tech, Math › Science Electron Density Definition in Chemistry Share Flipboard Email Print Electron density describes the probably of an electron in a volume. PASIEKA, 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 July 09, 2019 Electron density is a representation of the probability of finding an electron in a specific location around an atom or molecule. In general, the electron is more likely to be found in regions with high electron density. However, due to the uncertainty principle, it's not possible to identify the exact location of an electron at any instant in time. For a system with a single electron, electron density is proportion to the square of its wavefunction. X-ray diffraction crystallography is one technique used to measure electron density. When the concept is applied to free radicals, it is called spin density. This is the total electron density of one spin minus the electron density of electrons with the other spin. Neutron diffraction is used to map spin density.