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Electron Configurations

Electron Configurations. Bohr Model Issues. While the Bohr Model correctly positions electrons into energy levels, the true locations of electrons aren’t shown.

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Electron Configurations

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  1. Electron Configurations

  2. Bohr Model Issues While the Bohr Model correctly positions electrons into energy levels, the true locations of electrons aren’t shown. Instead of electrons following a set circular path around the nucleus, they are randomly found in regions of space we call orbitals.

  3. Quantum Mechanical Model This model uses probability functions to calculate an area of space that takes a specific shape around the nucleus. The orbital is the region where these electrons are found approximately 90% of the time.

  4. Quantum Numbers Principal Quantum Numbers: Show relative sizes and energy of orbital sublevelsn = 1 (1st level) n = 2 (2nd level) n = 3 (3rd level) n = 4 (4th level)

  5. Identifying n What is the principal energy level for the outermost electron in the following element?

  6. Identifying n What is the principal energy level for the outermost electron in the following element?

  7. Identifying n What is the principal energy level for the outermost electron in the following element?

  8. Orbital Basics Different orbitals have different shapes and sizes. Additional shapes are possible for orbitals in the same energy sublevel. s p d f

  9. Energy Sublevels There is a pattern to the location where the electrons are found on the periodic table.

  10. Orbital Sublevels In which orbital sublevel would you find the final electron for the atom below? 4s 3s 3p 2p

  11. Orbital Sublevels In which orbital sublevel would you find the final electron for the atom below? 2s 3s 3p 4p

  12. Orbital Sublevels In which orbital sublevel would you find the final electron for the atom below? 4d 4s 3d 4p

  13. Orbital Sublevels In which orbital sublevel would you find the final electron for the atom below? 5f 5d 7f 7s

  14. Energy Sublevels Once an orbital sublevel is filled, the next electron is placed in the next sublevel up. The type of orbital being filled determines the number of orbitals available in a sublevel. s: only 1 orbital per sublevel p: 3 orbitals per sublevel d: 5 orbitals per sublevel f: 7 orbitals per sublevel

  15. Electron Filling Principles • 1) The Aufbau Principle: • an electron will occupy the lowest energy position possible (Think 2-8-8 Rule)

  16. Electron Filling Principles • 2) Pauli Exclusion Principle: • A single orbital can hold at most 2 electrons (with opposite spin). • 3) Hund’s Rule: • An electron will fill an unoccupied orbital in an energy sublevel before sharing an orbital with another electron.

  17. Orbital Diagrams Orbital diagrams use the electron filling principles to show the number of orbitals that are filled, partially filled, or empty. Arrows represent electrons with up or down spin in an orbital. Oxygen 1s 2s 2p

  18. Orbital Diagram Practice True or False: the correct orbital diagram for sulfur is shown below

  19. Orbital Diagram Practice True or False: the correct orbital diagram for vanadium is shown below

  20. Orbital Diagram Practice True or False: the correct orbital diagram for copper is shown below

  21. An Easier Way… You’ll notice that if you show every electron being filled, larger atoms would take a very long time to write. We have electron configurations to help simplify that process. Electron configurations abbreviate an orbital sublevel with the sublevel-type-number notation. 2p4

  22. Electron Configurations Full electron configurations show all orbital sublevels in the order the electrons are filled up. 1s22s22p63s23p3 Shortened (noble gas) configurations start with the last noble gas electron filled and then the remaining electrons. [Ne]3s23p4

  23. Electron Configuration Practice Which of the following is the correct electron configuration for oxygen? • 1s22p6 • 1s2 2s22p4 • 2p4

  24. Electron Configuration Practice Which of the following is the correct electron configuration for potassium? 1s2 2s2 2p6 3s1 1s2 2s2 2p6 3s2 3p7 1s2 2s2 2p6 3s2 3p6 4s1

  25. Electron Configuration Practice Which of the following is the correct electron configuration for molybdenum? 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p65s24d4 1s2 2s2 2p6 3s2 3p6 4s2 4d10 4p65s25d4 1s2 2s2 2p6 3s2 3p6 4s23d10 4p6 5s1 4d5

  26. Short Configuration Practice Which of the following is the correct short-form electron configuration for silicon? [Ne] 3p2 [Ne] 3s23p2 [Ar] 3s23p2

  27. Short Configuration Practice Which of the following is the correct short-form electron configuration for chromium? • [Ar]4s23d4 • [Kr] 4s2 3d4 • [Ar] 4s13d5

  28. Short Configuration Practice Which of the following is the correct short-form electron configuration for lead? • [Xe]  6s2 4f14 5d10 6p2 • [Xe]  6s2 5d10 6p2 • [Xe]  6s2 6p2

  29. Lewis Symbols Lewis symbols show the element symbol surrounded by only electrons that fill the outer s & p orbitals. Cl Li C Al

  30. Lewis Symbol Practice Draw the Lewis Symbol for each of the following atoms: Ba N Pb Ag

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