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Quantum Numbers and Electron Configuration
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Quantum Numbers and Electron Configuration

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Quantum Numbers and Electron Configuration Quantum Numbers and Electron Configuration Presentation Transcript

  • a
  • QUANTUM MECHANICAL MODEL• Electron Cloud Model – Mathematical construct – Electron density (probability) – Atomic orbital (region)
  • QUANTUM NUMBERS• “address” of an electron • principal – n • angular momentum – l • magnetic – ml • electron spin – ms
  • Principal Quantum Number, n• Relative size/distance• Energy• (+) integer• Key: The light emitted by an electron moving from a higher to a lower energy level has a frequency directly proportional to the energy change of the electron. Each transition produces a line of a specific frequency in the spectrum. Lyman Series – lines at the ultraviolet end of hydrogen spectrum; “excited states; n=1 Balmer Series – lines in the visible spectrum; n=2 Paschen Series- lines in the infared range; n=3 Spectral lines in each group become more closely spaced at increased values of n because energy levels become closer together.
  • Angular Momentum Quantum Number, l• Orbital shape • s, p, d, and f: INCREASING ENERGY• Allowed values: s – sharp 0 to n - 1 p – principal d – diffuse f – fundamental
  • Angular Momentum Quantum Number, l• s orbital – Spherical – Electron density
  • Angular Momentum Quantum Number, l• p Orbital – Dumbbell-shaped – Electron density
  • Angular Momentum Quantum Number, l• d Orbital – Four-leaf clover – Electron density
  • Angular Momentum Quantum Number, l• f Orbital – “complex” shape – Electron density
  • Magnetic Quantum Number, ml• Orientation in space• Integral values between – l and l, including zero Value of l 0 1 2 3 Letter used s p d f
  • Magnetic Quantum Number, ml Value of l 0 1 2 3 Letter used s p d f• Enumerate ml for each orbital: –s –p –d –f
  • Additional Notes• Angular Momentum Quantum Number, l – Allowed values: 0 to n – 1 BACK
  • Magnetic Quantum Number, ml• Level or Shell – Orbitals with same n• Sublevel or Subshell – Orbitals with same n and l• Orbital
  • 3-minute Quiz  (1/4 sheet)I. (No need to copy the table) TOTAL: 10 pts QUANTUM NUMBER SYMBOL (1) (2) (3) (4) (5) (6) (7) (8)II. An energy sublevel with n = 5 and l = 1 has a 5p designation. What is the designation for a sublevel with n = 6 and l = 2? How many orbitals are in this sublevel?
  • Magnetic Spin Quantum Number, ms• Spectral line – NOT single but a closely spaced pair• 2 electrons (same charge) in one orbital?
  • Magnetic Spin Quantum Number, ms• Electron spin – Spinning charge – Magnetic field• 2 possible values: + ½ or –½ (a) cw* (b) ccw* *Left hand rule
  • Magnetic Spin Quantum Number, ms• Experimental Evidence for Electron Spin • Stern-Gerlach Experiment (1921)
  • Pauli Exclusion Principle• “No two electrons in an atom can have the same set of four quantum numbers n, l, ml and ms.” -Wolfgang Pauli (1925)
  • Summary Energy Sublevels Orbitals Levelsn=1 1s 1s (one)n=2 2s, 2p 2s (one) + 2p (three)n=3 3s, 3p, 3d 3s (one) + 3p (three) + 3d (five)n=4 4s, 4p, 4d, 4f 4s (one) + 4p (three) + 4d (five) + 4f (seven)
  • Example 1• Write a complete set of quantum numbers for n l ml ms all of the electrons in 5B. 1st e‾ 1 0 0 +½ 2nd e‾ 1 0 0 -½• Notes: 3rd e‾ 2 0 0 +½ – 2 electrons per orbital 4th e‾ 2 0 0 -½ – Allowed values for l are 0 to n – 1 5th e‾ 2 1 -1 +½ – Values for ml are - l to l, including zero Go to TABLE of n, l and ml
  • Example 2• Write a complete set of n l ml ml quantum numbers for all of the electrons in 1st e‾ 10Ne. (Notebook)• Notes: – 2 electrons per orbital – Allowed values for l are 0 to n – 1 – Values for ml are 10th e‾ -l , … , 0, … , l
  • Homework• 1 whole sheet• Write a complete set of quantum numbers for all of the electrons in 18Ar.• What are the quantum numbers of the 13th e‾?
  • SOURCE: http://mrselliott.wordpress.com/2011/09/08/electron-configuration-revision/
  • SOURCE: http://mrselliott.wordpress.com/2011/09/08/electron-configuration-revision/
  • [Strange] Apartment RULES (Required by the Building Owner, Sorry) • From the Bottom Up Fill the one room on the first floor before starting to put new tenants on the second floor. At higher floors the order might change a bit. • Singles First Have the tenants spread out as much as possible. If couples must be placed into a room then all of the other rooms on that floor must already have a single in them. • Opposite Gender Only No men may room together and no women may room together.
  • Electron Configuration [Strange] Apartment House Rules Electron Cloud House Rules• From the Bottom Up • Aufbau Principle Fill the one room on the first floor The electrons fill the available before starting to put new tenants orbitals from lowest energy to on the second floor. Note: At highest energy. higher floors the order might change a bit.• Singles First • Hund’s Rule Have the tenants spread out as Single electrons must be placed much as possible. If couples must into orbitals first and then paired be placed into a room then all of up if necessary. the other rooms on that floor must already have a single in them • Pauli Exclusion Principle Up and Down spins are always• Opposite Gender Only paired together and Up-Up or No men may room together and Down-Down combinations are no women may room together. not allowed.
  • Electron Rules• Aufbau Principle The electrons fill the available orbitals from lowest energy to highest energy. *Degenerate orbitals
  • Electron Configuration1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p INCREASING ENERGY
  • Order of orbitals (filling) in multi-electron atom1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p 7.7
  • Electron Configuration Si Sally pumasok sa pinto Sa door pinto Sa door pinto Sa front door pinto Sa front door pinto1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p
  • Electron Configuration• Orbital Diagram
  • Electron ConfigurationComplete electron configuration1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 6 6s 2 4f14 5d 10 6p 6 7s 2 5f14 6d10 7p6• Examples• Draw the orbital diagram
  • Electron Configuration RULES• Aufbau Principle The electrons fill the available orbitals from lowest energy to highest energy. Atomic Number = # of electrons• Hund’s Rule Single electrons must be placed into orbitals (boxes) first and then paired up if necessary.• Pauli Exclusion Principle Up and Down spins are always paired together and Up-Up or Down-Down combinations are not allowed.