Chem 18 Lec

• Electron spin quantum number, ms

  • ms does not depend on n, l, and ml
  • quantum number characterizing an electron:

  • s: magnitude of the magnetic field

  •ms: orientation of the magnetic field
• Pauli’s Exclusion Principle

  • in any given atom, no two electrons can have the same set of four quantum numbers

  • an orbital can only hold two electrons and these electrons must have two

  opposite spins
• Aufbau Principle

  • as protons are added one by one to the nucleus to build up the elements, electrons are similarly added to the orbitals
• electronic configuration

  • describes how electrons are distributed among the various atomic orbitals
• Hund’s Rule of Multiplicity

  • the most stable arrangement of electrons in subshells is the one with the

  greatest number of parallel spins
• Valence electrons are the electrons in the outermost principal quantum level of an atom.”
• • paramagnetic – contain net unpaired spins (attracted by a magnet)

  • diamagnetic – do not contain net unpaired spins (slightly repelled by a magnet)