electron configuration

• What is the arrangement of electrons in atoms described as?

  Complex with several levels of organization
• According to the Bohr model, how are electrons arranged?

  In shells defined by principal quantum number 'n'
• What is the principal quantum number symbol?


  'n'
• What is the lowest energy shell's principal quantum number?

  n = 1
• What happens to the energy of shells as 'n' increases?

  Energy increases with higher 'n'
• How does the distance from the nucleus change with increasing 'n'?

  Electrons orbit further from the nucleus
• What are sub-shells in atoms with more than one electron?

  They are divisions of shells with different energies
• How does the energy difference between sub-shells compare to shells?

  Sub-shell energy differences are much less
• How many sub-shells does a shell with principal quantum number 'n' have?

  n sub-shells
• How many sub-shells does the n = 3 shell have?

  Three sub-shells
• What are orbitals composed of?

  Sub-shells
• How many electrons can each orbital hold?

  Two electrons
• What is a set of orbitals with the same energy called?

  A sub-shell
• Do different sub-shells have the same energy?

  No, they do not have the same energy
• Why is the concept of an orbital important?

  It helps understand many chemical properties
• What are the first three types of orbitals?

  s, p, and d
• How many orbitals are in an s sub-shell?

  One s orbital
• How many orbitals are in a p sub-shell?

  Three p orbitals
• How many orbitals are in a d sub-shell?

  Five d orbitals
• What are orbitals of the same energy called?

  Degenerate orbitals
• How many sub-shells does the n = 1 shell have?

  One sub-shell
• What type of sub-shell does the n = 1 shell have?

  An s sub-shell
• How many sub-shells does the n = 2 shell have?

  Two sub-shells
• What sub-shells does the n = 2 shell have?

  An s sub-shell and a p sub-shell
• How many sub-shells does the n = 3 shell have?

  Three sub-shells
• What sub-shells does the n = 3 shell have?

  An s, p, and d sub-shell
• How are orbitals filled?

  From lowest energy to highest energy
• What is the usual energy order for filling orbitals?

  s ⇒ p ⇒ d
• What is the anomaly in filling orbitals for transition metals?

  4s is lower energy than 3d
• What is the filling order for transition metals?

  3s ⇒ 3p ⇒ 4s ⇒ 3d
• What are the three principles governing electron configuration?

  • Aufbau Principle: Fill from lowest to highest energy.
  • Pauli Exclusion Principle: Maximum of two electrons per orbital with opposite spins.
  • Hund’s Rule: Fill degenerate orbitals singly first.
• What happens to the 4s orbital when electrons are added or removed?

  Filled first and emptied before 3d
• How is electron configuration notation typically written?

  As a series of sublevel notations
• What is an exception to the Aufbau Principle?

  Chromium and Copper have unique configurations
• What provides extra stability in some elements' configurations?

  • Half-filled d-orbitals
  • Fully filled d-orbitals