Ionic Bonds & Lattice Structure (CIE IGCSE Chemistry)

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Lattice structure

• Ionic compounds have a giant lattice structure
• Lattice structure refers to the arrangement of the atoms of a substance in 3D space
• In lattice structures, the atoms are arranged in an ordered and repeating fashion
• The lattices formed by ionic compounds consist of a regular arrangement of alternating positive and negative ions
  
  

 The lattice structure of NaCl

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Ionic compounds

• Ionic compounds are formed when metal atoms and non-metal atoms react
• The ionic compound has no overall charge

Example:  Magnesium Oxide, MgO

Diagram showing the dot-and-cross diagram of magnesium oxide

 Explanation

• Magnesium is a Group II metal so will lose two outer electrons to another atom to have a full outer shell of electrons
• A positive ion with the charge 2+ is formed
• Oxygen is a Group VI non-metal so will need to gain two electrons to have a full outer shell of electrons
• Two electrons will be transferred from the outer shell of the magnesium atom to the outer shell of the oxygen atom
• Oxygen atom will gain two electrons to form a negative ion with charge 2-
• Magnesium oxide has no overall charge

Formula of ionic compound:    MgO