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Electron Configuration

Electron Configuration. Mapping the electrons. Electron Configuration. The way electrons are arranged around the nucleus. Quantum Mechanical Model. 1920’s-1930’s Werner Heisenberg (Uncertainty Principle) Louis de Broglie (electron has wave properties)

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Electron Configuration

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  1. Electron Configuration Mapping the electrons

  2. Electron Configuration • The way electrons are arranged around the nucleus.

  3. Quantum Mechanical Model • 1920’s-1930’s • Werner Heisenberg (Uncertainty Principle) • Louis de Broglie (electron has wave properties) • Erwin Schrodinger (mathematical equations using probability, quantum numbers)

  4. Heisenberg uncertainty principle • it is impossible to determine simultaneously both the position and velocity of an electron or any other particle with any great degree of accuracy or certainty.

  5. Erwin Schroedinger • Formulated equation that describes behavior and energies of subatomic particles. • Incorporates both particle and wave behavior in terms of wave function: is proportional to the probability of finding an electron.

  6. Erwin Schroedinger (cont’d) • Leads to Quantum Mechanics: we cannot pinpoint an electron in an atom but we can define the region where electrons can be in a particular time……. called a “probability map”….a 3-dimensional area in space called an ORBITAL

  7. Principal Quantum Number, n • Indicates main energy levels n = 1, 2, 3, 4… • Each main energy level has sub-levels s p d f

  8. Orbital Quantum Number, ℓ(Angular Momentum Quantum Number) • Indicates shape of orbital sublevels • ℓ = n-1 ℓ sublevel 0 s 1 p 2 d 3 f 4 g

  9. Quantum numbers and orbital energiesEach electron in an atom has a unique set of quantum numbers to define it{ n, l, ml, ms } • n = principal quantum number • electron’s energy depends principally on this • l = azimuthal quantum number • for orbitals of same n, l distinguishes different shapes (angular momentum) • ml = magnetic quantum number • for orbitals of same n & l, ml distinguishes different orientations in space • ms = spin quantum number • for orbitals of same n,l & ml, ms identifies the two possible spin orientations

  10. Energy levelSublevel# of orbitals/sublevel n = 1 1s (l = 0) 1 (ml has one value) n = 22s (l = 0) 1 (ml has one value) 2p (l = 1) 3 (ml has three values) n = 33s (l = 0) 1 (ml has one value) 3p (l = 1) 3 (ml has three values) 3d (l = 2) 5 (ml has five values) n = principal quantum number (energy) ml = magnetic quantum number (orientation) l = azimuthal quantum number (shape)

  11. Concept: Each electron in an atom has a unique set of quantum numbers to define it{ n, l, ml, ms } 11

  12. The principle quantum number, n, determines the number of sublevels within the principle energy level.

  13. Orbital • The space where there is a high probability that it is occupied by a pair of electrons. • Orbitals are solutions of Schrodinger’s equations.

  14. Orbitals

  15. Visualizing the orbitals • s orbitals are spherical • p orbitals are “dumbell” shaped • d and f are harder to visualize

  16. Orbitals in Sublevels Sublevel # Orbitals # electrons s 1 2 p 3 6 d 5 10 f 7 14

  17. Three rules are used to build the electron configuration: • Aufbau principle • Pauli Exclusion Principle • Hund’s Rule

  18. Aufbau Principle • Electrons occupy orbitals of lower energy first.

  19. Orbital Diagram

  20. Filling Order diagram

  21. -Pauli Exclusion Principle(Wolfgang Pauli, Austria, 1900-1958)-Electron Spin Quantum Number • An orbital can hold only two electrons and they must have opposite spin. • Electron Spin Quantum Number (ms): +1/2, -1/2

  22. Hund’s Rule In a set of orbitals, the electrons will fill the orbitals in a way that would give the maximum number of parallel spins (maximum number of unpaired electrons). Analogy: Students could fill each seat of a school bus, one person at a time, before doubling up.

  23. Orbital Diagram for Hydrogen

  24. OrbitalDiagram for Helium

  25. Orbital Diagram for Lithium

  26. Orbital Diagram for Beryllium

  27. Orbital Diagram for Boron

  28. OrbitalDiagram for Carbon

  29. Orbital Diagram for Nitrogen

  30. Orbital Diagram

  31. Notations of Electron Configurations • Standard • Shorthand

  32. Orbital Diagram for Fluorine

  33. Standard Notation of Fluorine Number of electrons in the sub level 2,2,5 1s22s22p5 Main Energy Level Numbers 1, 2, 2 Sublevels

  34. Shorthand Notation • Use the last noble gas that is located in the periodic table right before the element. • Write the symbol of the noble gas in brackets. • Write the remaining configuration after the brackets. • Ex: Fluorine: [He] 2s2 2p5

  35. Blocks in the Periodic Table

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