4.1 Ionic bonding and structure

Ionic Bonding

  • Ionic Bond is due to electrostatic attraction between oppositely charged ions
  • Ions are formed when one or more electrons are transferred from one atom to another
  • The number of electrons lost or gained is determined by the electron configuration of the atom
  • The reason there is transfer of electrons is because they want to achieve a noble gas configuration
  • Positive ions (Cations) form by metals losing valence electrons
  • Negative Ions (Anions) form by non-metals gaining electrons
    • OIL RIG
      • Oxidation Is Loss of electrons
      • Reduction Is Gain of electrons
    • Ionic compounds are typically solids and have lattice-type structures that consist of 3D repeating units of positive and negative ions


Easy way to memorize all the oxyanions is to remember the following sentence, and the rules to go with them.

  • Consonants are the number of oxygens, vowels is the charge.


Let’s take premium (PO43-) for example:

  • Premium there are 3 vowels. Thus the charge is 3-
  • Premium there are 4 consonants, thus there are 4 oxygen’s
  • PO43-

Physical Properties

  • Volatility
    • Tendency to vaporize. Ionic compounds have strong electrostatic forces thus they have low volatility
  • Electrical Conductivity
    • For ionic compound in solid state, ions occupy fixed position. Hence, they do not move around or conduct electricity. In molten state they are free to do so.
  • Solubility
    • Ionic compounds dissolve in polar solvents such as water
    • This is because partial charges of polar solvents are attracted to ions in the lattice
    • As result, individual ions are pulled out of lattice structure

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