AQA · GCSE · Combined Science
Course version: 8464 · Version from Sept 2018
Chemical bonds: Ionic bonding occurs in compounds formed from metals combined with non-metals.
Ionic bonding happens when a metal reacts with a non-metal.
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
Ionic bonding happens when a metal reacts with a non-metal. Metal atoms lose electrons to form positive ions, while non-metal atoms gain those electrons to form negative ions. The oppositely charged ions are held together by strong electrostatic attraction in a giant ionic lattice. For example, sodium (a Group 1 metal) transfers one electron to chlorine (a Group 7 non-metal), producing Na⁺ and Cl⁻ ions in sodium chloride. The compound is neutral overall because the total positive charge balances the total negative charge. This explains why ionic compounds have high melting and boiling points, conduct electricity when molten or dissolved, and often dissolve in water. The key idea is that ionic bonding is identified from the metal-plus-non-metal combination, not from the name alone.
What earns the marks
- Identify that ionic bonding occurs between a metal and a non-metal, for example sodium and chlorine in sodium chloride.
- Describe electron transfer: metal atoms lose electrons to form positive ions and non-metal atoms gain electrons to form negative ions.
- State that the ions formed have full outer shells and are held in a giant ionic lattice by strong electrostatic attraction.
- Explain that the overall compound is neutral because the total positive charge equals the total negative charge.
- Link the structure to a property, such as high melting point or conduction when molten or aqueous, to show understanding of the bonding model.
Common mistakes and how to put them right
Writing that ionic bonds form between two non-metals.
Put it right by checking that one element is a metal and the other is a non-metal.
Saying that atoms share electrons in ionic bonding.
Put it right by describing transfer of electrons to form ions.
Drawing ions without charge labels or with incorrect charges.
Put it right by showing Na⁺ and Cl⁻, and balancing charges such as Mg²⁺ with two Cl⁻ ions.
Exam tips
- Underline the metal and non-metal in the question before deciding whether ionic bonding is present.
- When drawing dot-and-cross diagrams for ionic compounds, show the transfer of electrons and include the charge on each ion.
- Use the phrase 'strong electrostatic attraction between oppositely charged ions' when explaining properties of ionic compounds.
Try the lesson
The start of the Chemical bonds: Ionic bonding occurs in compounds formed from metals combined with non-metals. lesson, made from checked teaching notes for this specification point.
Have a go first
Which combination of element types typically forms an ionic bond?
Key words
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Electron transfer between atoms
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Formation of positive and negative ions
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Giant ionic lattice structure
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Relationship between bonding, structure and properties
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See every definition
- Electron transfer between atoms
- Metal atoms lose electrons to form positive ions, while non-metal atoms gain those electrons to form negative ions.
- Formation of positive and negative ions
- Metal atoms lose electrons to form positive ions, while non-metal atoms gain those electrons to form negative ions.
- Giant ionic lattice structure
- Oppositely charged ions are held together by strong electrostatic attraction in a giant ionic lattice.
- Relationship between bonding, structure and properties
- The giant ionic lattice explains why ionic compounds have high melting and boiling points, conduct electricity when molten or dissolved, and often dissolve in water.
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