Science, Tech, Math › Science S P D F Orbitals and Angular Momentum Quantum Numbers What You Need to Know About Orbital Name Abbreviations Share Flipboard Email Print This is a graphic representation of the 4fz3 electron orbital. Photo from Amazon Science Chemistry Physical Chemistry Basics Chemical Laws Molecules Periodic Table Projects & Experiments Scientific Method Biochemistry 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 May 07, 2019 The orbital letters are associated with the angular momentum quantum number, which is assigned an integer value from 0 to 3. The s correlates to 0, p to 1, d to 2, and f to 3. The angular momentum quantum number can be used to give the shapes of the electronic orbitals. What Does S, P, D, F Stand For? The orbital names s, p, d, and f stand for names given to groups of lines originally noted in the spectra of the alkali metals. These line groups are called sharp, principal, diffuse, and fundamental. Shapes of Orbitals and Electron Density Patterns The s orbitals are spherical, while p orbitals are polar and oriented in particular directions (x, y, and z). It may be simpler to think of these two letters in terms of orbital shapes (d and f aren't described as readily). However, if you look at a cross-section of an orbital, it isn't uniform. For the s orbital, for example, there are shells of higher and lower electron density. The density near the nucleus is very low. It's not zero, however, so there is a small chance of finding an electron within the atomic nucleus. What the Orbital Shape Means The electron configuration of an atom denotes the distribution of electrons among available shells. At any point in time, an electron can be anywhere, but it's probably contained somewhere in the volume described by the orbital shape. Electrons can only move between orbitals by absorbing or emitting a packet or quantum of energy. The standard notation lists the subshell symbols, one after another. The number of electrons contained in each subshell is stated explicitly. For example, the electron configuration of beryllium, with an atomic (and electron) number of 4, is 1s22s2 or [He]2s2. The superscript is the number of electrons in the level. For beryllium, there are two electrons in the 1s orbital and 2 electrons in the 2s orbital. The number in front of the energy level indicates relative energy. For example, 1s is lower energy than 2s, which in turn is lower energy than 2p. The number in front of the energy level also indicates its distance from the nucleus. The 1s is closer to the atomic nucleus than 2s. Electron Filling Pattern Electrons fill up energy levels in a predictable manner. The electron filling pattern is: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f s can hold 2 electronsp can hold 6 electronsd can hold 10 electronsf can hold 14 electrons Note that individual orbitals hold a maximum of two electrons. There can be two electrons within an s-orbital, p-orbital, or d-orbital. There are more orbitals within f than d, and so on.