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Observing the Effect of Electron Spin

Electron Configuration and Chemical Periodicity-EXERCISE. Observing the Effect of Electron Spin. principal. n. positive integers (1, 2, 3,…). orbital energy (size). angular momentum. l. integers from 0 to n -1.

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Observing the Effect of Electron Spin

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  1. Electron Configuration and Chemical Periodicity-EXERCISE Observing the Effect of Electron Spin

  2. principal n positive integers (1, 2, 3,…) orbital energy (size) angular momentum l integers from 0 to n-1 orbital shape (l values of 0, 1, 2 and 3 correspond to s, p, d and f orbitals, respectively.) magnetic ml integers from -l to 0 to +l orbital orientation spin ms +1/2 or -1/2 direction of e- spin Table 8.2 Summary of Quantum Numbers of Electrons in Atoms Name Symbol Allowed Values Property Each electron in an atom has its own unique set of four (4) quantum numbers.

  3. The Pauli Exclusion Principle No two electrons in the same atom can have the same four quantum numbers An atomic orbital can hold a maximum of two electrons and they must have opposite spins (paired spins) General Rule for Predicting Relative Sublevel Energies For a given n value, the lower the l value, the lower the sublevel energy; thus…. s < p < d < f

  4. Hund’s Rule When orbitals of equal energy are available, the electron configuration of lowest energy has the maximum number of unpaired electrons with parallel spins.

  5. PROBLEM: Write a set of quantum numbers for the third electron and a set for the eighth electron of the fluorine (F) atom. 9F 1s 2s 2p n = n = l = l = ml = ml = ms= ms= Determining Quantum Numbers from Orbital Diagrams Sample Problem 1 PLAN: Use the orbital diagram to find the third and eighth electrons. Up arrow = +1/2 Down arrow = -1/2 SOLUTION: The third electron is in the 2s orbital. Its quantum numbers are: 2 0 0 +1/2 The eighth electron is in a 2p orbital. Its quantum numbers are: 2 1 -1 -1/2

  6. Orbital occupancy for the first 10 elements, H through Ne Figure 1 He and Ne have filled outer shells: confers chemical inertness

  7. Condensed ground-state electron configurations in the first three periods Figure 2 Similar outer electron configurations correlate with similar chemical behavior.

  8. Cr and Cu: Half-filled and filled sublevels are unexpectedly stable!

  9. A periodic table of partial ground-state electron configurations Figure 8.12

  10. The relation between orbital filling and the Periodic Table Figure 8.13

  11. Common tool used to predict the filling order Of sublevels n values are constant horizontally l values are constant vertically combined values of n+1 are constant diagonally p. 302

  12. Categories of Electrons Inner (core) electrons: fill all the lower energy levels of an atom Outer electrons: those electrons in the highest energy level (highest n value) of an atom Valence electrons: those involved in forming compounds; the bonding electrons; among the main-group elements, the valence electrons are the outer electrons

  13. General Observations about the Periodic Table A. The group number equals the number of outer electrons (those with the highest value of n) (main-group elements only) B. The period number is the n value of the highest energy level. C. The n value squared (n2) gives the total number of orbitals in that energy level; 2n2 gives the maximum number of electrons in the energy level. KEY PRINCIPLE All physical and chemical properties of the elements are based on the electronic configurations of their atoms.

  14. PROBLEM: Using the periodic table, give the full and condensed electron configurations, partial orbital diagrams showing valence electrons, and number of inner electrons for the following elements: full configuration: condensed configuration: partial orbital diagram: 4s1 SAMPLE PROBLEM 2 Determining Electron Configuration (a) potassium (K: Z = 19) (b) molybdenum (Mo: Z = 42) (c) lead (Pb: Z = 82) PLAN: Use the atomic number for the number of electrons and the periodic table for the order of filling of the electron orbitals. Condensed configurations consist of the preceding noble gas plus the outer electrons. SOLUTION: (a) for K (Z = 19) 1s22s22p63s23p64s1 [Ar] 4s1 K has 18 inner electrons.

  15. full configuration: condensed configuration: partial orbital diagram: 5s1 4d5 full configuration: condensed configuration: partial orbital diagram: 6s2 6p2 SAMPLE PROBLEM 2: (continued) (b) for Mo (Z = 42) 1s22s22p63s23p64s23d104p65s14d5 [Kr] 5s14d5 Mo has 36 inner electrons and 6 valence electrons. (c) for Pb (Z = 82) 1s22s22p63s23p64s23d104p65s24d105p66s24f145d106p2 [Xe] 6s24f145d106p2 Pb has 78 inner electrons and 4 valence electrons.

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