Electronic configuration

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Electronic configuration

  1. 1. ELECTRONIC CONFIGURATION
  2. 2. Electronic Configuration of an Atom - the arrangement of electrons in the orbital of an atom. - described by a. a number that designates the number of principal shell b. a letter that designates the subshell (orbital) c. a subscript that designates the number of electrons in that particular subshell (orbital) Example: 2p4 indicates 4 electrons in the p subshell of the 2nd shell. 3d8 indicates 8 electrons in the d subshell of the 3rd shell.
  3. 3. Figure 8.12 The relation between orbital filling and the periodic table
  4. 4. Figure 8.11 A periodic table of partial ground-state electron configurations
  5. 5. <ul><li>Aufbau (building-up) Principle </li></ul><ul><li>“ Electrons in an atom occupy first the lowest possible energy levels and/or orbitals.” </li></ul><ul><li>Order: 1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4f 5d 6p 7s 5f 6d 7p </li></ul>
  6. 6. b. Pauli’s Exclusion Principle “ No two electrons in the same atom can have the same set of four quantum numbers, i.e., the maximum number of electron in an orbital is limited to two.” *for 1s orbital: one electron: n=1, l=0, ml=0,ms=+½ one electron: n=1, l=0, ml=0,ms=-½
  7. 7. c. Hund’s Rule “Every orbital in a subshell (degenerate orbitals) is occupied (filled) with one electron first before any one orbital is doubly-filled, and all electrons in singly-occupied orbitals have the same spin.”
  8. 9. Figure 8.11 A periodic table of partial ground-state electron configurations
  9. 10. SAMPLE PROBLEM 8.2 Determining Electron Configuration PLAN: SOLUTION: (a) potassium (K: Z = 19) (b) molybdenum (Mo: Z = 42) (c) lead (Pb: Z = 82) Use the atomic number for the number of electrons and the periodic table for the order of filling for electron orbitals. Condensed configurations consist of the preceding noble gas and outer electrons. (a) for K (Z = 19) 1s 2 2s 2 2p 6 3s 2 3p 6 4s 1 [Ar] 4s 1 There are 18 inner electrons. PROBLEM: Using the periodic table give the full and condensed electrons configurations, partial orbital diagrams showing valence electrons, and number of inner electrons for the following elements: 4s 1 condensed configuration partial orbital diagram full configuration 3d 4p
  10. 11. SAMPLE PROBLEM 8.2 continued (b) for Mo (Z = 42) 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 1 4d 5 [Kr] 5s 1 4d 5 (c) for Pb (Z = 82) [Xe] 6s 2 4f 14 5d 10 6p 2 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 6 6s 2 4f 14 5d 10 6p 2 There are 36 inner electrons and 6 valence electrons. There are 78 inner electrons and 4 valence electrons. condensed configuration partial orbital diagram full configuration 5s 1 4d 5 condensed configuration partial orbital diagram full configuration 6s 2 6p 2 5p
  11. 12. *Isoelectronic – atoms or ions of different elements that have the same electronic configuration. *An orbital can hold a maximum of 2 electrons of opposite spins. * Valence electrons – outer shell electrons * Diamagnetism – slightly affected by magnetic field * Paramagnetism – greatly affected by magnetic field (atoms with unpaired electrons)

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