Quantum Numbers and Electron Configuration

Quantum Numbers

  • Quantum numbers are the distribution of electrons in an electron; orientation of orbitals
Four Quantum Numbers
  • Principal Quantum Numbers - main energy level
      * princical quantum numbers are denoted by n
      * a principal quantum number’s values are positive integers (1,2,3,4…)

     

  • Azimuthal Quantum Number
      * azimuthal quantum numbers - describe the shape of an orbital
      * azimuthal quantum numbers are denoted by l.
      * azimuthal quantum numbers are also known as “angular momentum”
      * The shapes of an azimuthal quantum number consists of the: sphere, dumbell, double dumbell, multiple
        * s - 0
        * p - 0,1
        * d - 0,1,2
        * f - 0,1,2,3

     

  • Magnetic Quantum Numbers - are orientations of orbitals
      * orbitals - place or location wherein electrons are created
      * the values of magnetic quantum #s are: -3,-2,-1,0,1,2,3
      * magnetic quantum #s are denoted by - Ml
  • Spin Quantum Numbers - this quantum no. focuses on the direction of the electron
      * the values of spin quantum numbers are: +1/2,-1/2
      * spin quantum numbers are denoted by Ms

Electron Distribution

  • Electron distribution is the arrangement of electrons in the space around the nucleus of an atom; distribution of electrons in the orbitals of an atom
      * electron distribution uses symbols of orbitals and the number of electrons (written as a superscript) that occupy each orbital
        * the number of electrons is written as a superscript

Two Types of Configuration

  • Electronic Configuration
  • Orbital Diagram

Different Principles

  • Aufbau’s Principle - states that electrons should occupy the lowest orbital before those w/ highest energy level
  • Pauli’s Exclusion Principle - no two elements in an atom can possess the same set of quantum numbers
  • Hud’s Rule - most stable arrangement of electrons in subshell is the one w/ greatest no. of parallel spins

Parts of an Electron Configuration

 do note orbital=subshell

Maximum no. of Electrons

  • s - 2 (subshell), -1 (orbit)
  • p - 6 (subshell), -3 (orbit)
  • d - 10 (subshell), -5 (orbit)
  • f - 14 (subshell), -7 (orbit)

1s, 2s, 3p, 3s, 3p, 4s, 3d, 4p, 4d, 4d, 5p, 6s, 4f

Max no. of Energy Distribution

  • 1st - 2
  • 2nd - 8
  • 3rd -18
  • 4th - 32