Quantum Numbers Electron Configuration

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					Quantum Numbers & Electron
      Configuration
      Heisenberg uncertainty
            principle:
• States that it is impossible to determine
  both the position and velocity of an
  electron.
           Quantum Theory
• Schrodinger hypothesized that electrons
  have a dual wave-particle nature.
• Quantum theory describes wave
  properties of electrons – if an electron
  behaved ONLY like a particle, it would be
  much easier to determine its location and
  path.
  – An orbital is the area where an electron is
    probably located!
        Quantum Numbers
• Quantum numbers are used to specify the
  properties of atomic orbitals and the
  properties of electrons in orbitals
  – There are 4 quantum numbers!
         Quantum Numbers
1. PRINCIPAL Quantum Number – n
   *describes the principal (main) energy
   levels of electrons in an atom
   * increase in n = increase in energy
   * maximum number of electrons in an
   energy level
                Quantum Numbers
Angular Quantum Number – l
    * determines the shape of the orbital
    * the number of sublevels is equal to the principal quantum number
    * four shapes of the energy sub levels are:
                  »   s = spherical (groups 1&2)
                  »   p = dumbbell (groups 13-18)
                  »   d = double dumbbell (groups 3-12)
                  »   f = too complex to describe (groups 4-5)




     * Each of the sublevels (s, p, d, f) contain orbitals
     * Each orbital can hold 2 electrons
                  »   s = 1 orbital      = 2 e-
                  »   p = 3 orbitals     = 6 e-
                  »   d = 5 orbitals     = 10 e-
                  »   f = 7 orbitals     = 14 e-
          Quantum Numbers
MAGNETIC Quantum
 Number - m
 * describes the
 orientation (direction)
 of the orbital in space
 (x, y or z axis)
 * the number of
 orbitals = the number
 of different
 orientations
         Quantum Numbers
SPIN Quantum Number
   * describes the direction of the electron
   spin
   * spins clockwise (+ ½) or
   counterclockwise (– ½)
   * two electrons in the same orbital MUST
   HAVE OPPOSITE SPINS!!!
  Three Rules for writing notations
(determining how energy levels are filled
               in atoms)


           Aufbau principle
* electrons enter orbitals of the lowest energy
  first
 Three Rules for writing notations -
determining how energy levels are filled
              in atoms

            Pauli exclusion principle
* this limits the number of electrons in each
   orbital to 2: 1 spin up ↑, and 1 spin down ↓
 Three Rules for writing notations -
determining how energy levels are filled
              in atoms

                Hund’s Rule
* when electrons occupy orbitals of equal
  energy, ONE electron enters each orbital
  until ALL are ½ filled with electrons
  spinning in the same direction (all up or all
  down), then the orbitals are filled with the
  spin electrons