Ionic Bonds & Lattice Structure (Cambridge (CIE) IGCSE Chemistry)
Revision Note
Written by: Caroline Carroll
Reviewed by: Stewart Hird
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The lattice structure of ionic compounds
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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
Ionic bonds between metallic & non-metallic elements
Extended tier only
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
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
MgO
Diagram showing the dot-and-cross diagram of magnesium oxide
Examiner Tips and Tricks
When drawing dot and cross diagrams, you only need to show the outer shell of electrons. Remember to draw square brackets and include a charge for each ion. Make sure the overall charge is 0; you may need to include more than one positive or negative ion to ensure the positive and negative charges cancel each other out.
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