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Electron Configurations Electron Configurations The quantum mechanical model of the atom predicts energy levels for electrons; it is concerned with probability, or likelihood, of finding electrons in a certain position. z “Any one who is not shocked by Quantum theory does not understand it.” Niels Bohr Electron Configurations z Electron Configurations Regions where electrons are likely to be found are called orbitals. EACH ORBITAL CAN HOLD UP TO 2 ELECTRONS! z Electron Configurations In quantum theory, each electron is assigned a set of quantum numbers z analogy: like the mailing address of an electron Electron Configurations Start Filling Here 1 Electron Configurations Playing Chopin with Boxing Gloves z “Trying to capture the physicists’ precise mathematical description of the quantum world with our crude words and mental images is like playing Chopin with a boxing glove on one hand and a catcher’s mitt on the other.” (1996). Johnson, George. On skinning Schrodinger’s Cat. New York Times. Principal Quantum Number (n) Erwin Schrödinger I don’t like it, and I’m sorry I ever had anything to do with it. z Describes the energy level that the electron occupies n=1 z n=1, 2, 3, 4 n=2 n=3 n=4 z The larger the value of n, the farther away from the nucleus and the higher the energy of the electron. Sublevels (l) z z The number of sublevels in each energy level is equal to the quantum number, n, for that energy level. Sublevels are labeled with a number that is the principal quantum #, and a letter: s, p, d, f (ex: 2 p is the p sublevel in the 2nd energy level) 2 Sublevels (l) Sublevels (l) Principal Energy Level Sublevels Orbitals n=1 1s one (1s) n=2 2s 2p one (2s) three (2p) n=3 3s 3p 3d one (3s) three (3p) five (3d) 4s 4p 4d 4f one (4s) three (4p) five (4d) seven (4f) n=4 z Labels the orientation of the electron Electrons in an orbital spin in opposite directions; these directions are designated as +1/2 and -1/2 Orbitals of equal energy are each occupied by one electron before any pairing occurs. z z z Max # of electrons s 1 2 p 3 6 d 5 10 f 7 14 z States that no 2 electrons have an identical set of four quantum #’s to ensure that no more than 2 electrons can be found within a particular orbital. Orbital Diagrams Hund’s Rule z # of orbitals Pauli Exclusion Principle Spin quantum number (ms) z Sublevel z z Each orbital is represented by a box. Each electron is represented by an arrow. Repulsion between electrons in a single orbital is minimized All electrons in singly occupied orbital must have the same spin. When 2 electrons occupy an orbital they have opposite spins. 3 Complete electron configurations Orbital Diagrams z 1s z z helium 1s2 z boron 1s22s22p1 z neon 1s22s22p6 z aluminum 1s22s22p63s23p1 z uranium hydrogen helium 1s z carbon 1s 2s 2p 1s22s22p63s23p64s23d104p65s24d105p66s24f145d106p67s25f4 Abbreviated electron diagrams 1s2 z helium z boron z aluminum [Ne]3s23p1 z cobalt [He]2s22p1 [Ar]4s23d7 z N3- [He]2s22p6 = [Ne] z Se2- [Kr] z Mg2+ z uranium [Rn]7s25f4 [Ne] 4