ELECTRON CONFIGURATION

• electrons can be found at specific distances

  from the nucleus, called energy levels or electron shells.
• An

  atom's energy level, represented by the letter n, can assume whole

  number values from n = 1 to infinity.
• The distance from the nucleus increases with each energy

  level.
• Each energy level can only accommodate a specific number of

  electrons.
• The number of sublevels in each energy

  level increases with each energy level.
• Four sublevels

  • s
  • p
  • d
  • f
• A sublevel is represented by the number of the energy level it

  is in, followed by the letter of the sublevel (e.g., 1s, 2p, or 3d).
• • s=2
  • p=6
  • d=10
  • f=14
• The

  probable distribution of electrons around the nucleus

  among the orbitals is called electron configuration.
• Electron configuration is the shorthand representation

  of how each electron is arranged among the orbitals,

  levels, and sublevels based on the stated principles.
• ground state electron configuration is the most stable and the normal way atoms exist.
• The Aufbau (a German word that means "building up or

  construction") principle states that electrons fill first the orbitals of

  the lowest energy (ground state) until any added electrons occupy

  the available orbital of higher energy (excited state).
• The noble gasses (Group 8A) are located in the far right of the periodic table and were previously

  referred to as the "inert gasses" because their filled valence shells (octets) make them extremely non-

  reactive. They are helium, neon, argon, krypton, xenon, and radon.