Ionic Bonding (Oxford AQA International A Level Chemistry)

Ionic Bonding

• Ionic bonding is defined as the electrostatic attraction between oppositely charged ions in a lattice

• It involves the transfer of electrons from a metallic element to a non-metallic element

• Transferring electrons usually leaves the metal and the non-metal with a full outer shell

• Metals lose electrons from their valence shell forming positively charged cations

  • Na⁺, K⁺, Mg²⁺, Ca²⁺

• Non-metal atoms gain electrons forming negatively charged anions

  • F^-, Cl^-, O^2-, N^3-

• The number of electrons lost or gained will be the same as the charge

  • Na loses one electron to form the Na⁺ ion

• Once the atoms become ions, their electronic configurations are the same as a noble gas

  • Argon has the electronic configuration 1 s² 2s² 2p⁶ 3s² 3p⁶

Table of electronic configurations of atoms and ions

Ionic bonding formation in NaCl

• The ions form a lattice structure which is an evenly distributed crystalline structure

• Ions in a lattice are arranged in a regular repeating pattern so that positive charges cancel out negative charges

• The attraction between the cations and anions is occurring in all directions

  • Each ion is attracted to all of the oppositely charged ions around it

• Therefore the final lattice is overall electrically neutral

 Ionic crystal

Formulas of Ionic Compounds

• The charge for an ion can be determined by the group number:

Table showing the relationship between group number and charge

• You need to know the formulas for ions that compound

Names and formulas of compound ions