S P D F Orbitals and Angular Momentum Quantum Numbers

S P D F Orbitals and Angular Momentum Quantum Numbers 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 arent described as readily). However, if you look at a cross-section of an orbital, it isnt uniform. For the s orbital, for example, there are shells of higher and lower electron density. The density near the nucleus is very low. Its 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 its 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.