Chemistry Notes: Atomic Structure and Electron Configuration

Atomic Structure

• Subatomic particles:
  • Electron (e-) - JJ Thomson
  • Proton (p+) - Eugene Goldstein
  • Neutron (n0) - James Chadwick
• Nucleus discovered by Ernest Rutherford.

Atomic Models

• Dalton's Model by John Dalton
• Thomson's Model (plum-pudding model) by JJ Thomson
• Nuclear Model by Ernest Rutherford (Nucleus, Electrons, Empty space)
• Bohr's Model by Neils Bohr

Energy Levels

• Energy level represented by "n".
  • n1 = energy level 1
  • n2 = energy level 2
  • n3 = energy level 3
  • n4 = energy level 4
• Maximum number of electrons per energy level: 2n^2
  • n1 = 2 e-
  • n2 = 8 e-
  • n3 = 18 e-
  • n4 = 32 e-
• Subshells and their electron capacities:
  • s = 2 e-
  • p = 6 e-
  • d = 10 e-
  • f = 14 e-

Electron Configuration

• Distribution of electrons in energy levels.
• Valence electrons (ve-).
• Period (p) = highest energy level reached.
• Group (g) based on valence electrons.
• Family (A or B) based on shells containing valence electrons:
  • A - ending with 's' or 'sxp'
  • B - ending with 'sad'

Special Cases in Family B

• If valence electrons are 9 or 10, group is 8.
• If valence electrons are 11 or 12, subtract 10 to find the group.

Octet Rule

• Maximum valence electrons is 8.