Ionic Bonding Notes

Octagonal Prism/Pyramid

  • The shape (octagonal prism or pyramid) depends on the size of the atoms, specifically their radii, and the stoichiometry (how they join together).

Ionic Bonding

  • Electrons transfer from the cation (positively charged ion) to the anion (negatively charged ion).
  • This transfer results in the atoms becoming ions, and the bond formed is called ionic bonding.
  • Ionic bonding is an electrical force, specifically an electrostatic attraction, due to the charge between ions.
  • The magnitude (strength) of the attraction depends on:
    • The size of the ions involved.
    • The charge of the ions involved.
  • Larger atoms with many missing outer electron shells can form stronger bonds.
  • Smaller atoms tend to form less strong bonds.

Valence Electrons and Periodic Table Groups

  • The strength of ionic bonds is related to the number of valence electrons missing.
  • The number of valence electrons is related to the group that the element is in on the periodic table (groups +1, +2, +3 tend to lose electrons; -1, -2, -3 tend to gain electrons).
  • Whether an atom gains or loses electrons depends on how full its outer electron shells are.
  • The key principle of ionic bonding is sharing (transferring) of one or more electrons.

Properties of Ionic Compounds

  • Hard solids.
  • Crystalline structure.
  • Brittle.
  • High melting point (hard to break apart into a liquid).
  • Do not conduct electricity in solid form because electrons are bonded and not free to move.
  • Conduct electricity in liquid form.