Metallic bonding — AQA GCSE Chemistry
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Metallic bonding explained
Metallic bonding covers 2 specification points, including Metals consist of giant structures of atoms… and AQA GCSE Chemistry 8462.
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GCSE exams Jun. Open a point below for its explanation and revision guidance.
Metals consist of giant structures of atoms arranged in a regular pattern.
Metals are not made of separate molecules but of one enormous lattice of atoms. In a pure metal, identical atoms pack together in a repeating three-dimensional arrangement, so the structure is described as giant and regular. Because the lattice continues throughout the piece of metal, melting requires overcoming the strong metallic bonds between positive metal ions and delocalised electrons, explaining the high melting points of most metals. The regular packing also allows layers of atoms to slide over one another when a force is applied, so metals can be bent and shaped. For example, in a copper wire the copper atoms form a continuous regular lattice rather than a collection of Cu₂ molecules. When you describe a metal, state that it is a giant structure, that the atoms are arranged in a regular pattern, and that this arrangement extends throughout the material.
The electrons in the outer shell of metal atoms are delocalised and so are free to move through the whole structure. The sharing of delocalised electrons gives rise to strong metallic bonds. The bonding in metals may be represented in the following form: AQA GCSE Chemistry 8462. GCSE exams Jun
In a metal, the outer-shell electrons are not held by any one atom. They become delocalised, meaning they are shared across the whole giant lattice and are free to move. The positive metal ions that remain are arranged in a regular pattern, and the sea of delocalised electrons is attracted to these ions in all directions. This electrostatic attraction between the positive ions and the shared electrons is the metallic bond, and because it acts throughout the structure it is strong. The model is often drawn as positive ions in a regular lattice with negative delocalised electrons between them. Moving electrons explain why metals conduct electricity and heat, while the strong bonding explains high melting points. When answering, refer to delocalised electrons, free movement, positive ions and strong electrostatic attraction.
Your focus
- Describe a metal as a giant structure of atoms in a regular pattern.
- Represent the regular lattice of a metal using a simple diagram.
- Relate the giant regular structure and strong metallic bonds to at least one physical property of a metal.
Show all 6 objectives
- Describe delocalised electrons as outer-shell electrons free to move through a metal.
- Explain metallic bonding as the attraction between positive ions and delocalised electrons.
- Use the metallic bonding model to explain conductivity and high melting points.
Metallic bonding exam tips
Marking Points
- States that a metal is a giant structure rather than a simple molecule.
- Describes the atoms as arranged in a regular, repeating pattern.
- Explains that the regular lattice extends throughout the whole piece of metal.
- Links the giant regular structure and strong metallic bonds to a property such as high melting point or malleability.
- Uses the term lattice correctly to mean a repeating three-dimensional arrangement of atoms.
- States that outer-shell electrons in a metal become delocalised.
- Explains that delocalised electrons are free to move through the whole structure.
- Describes the metal as positive ions in a regular lattice surrounded by delocalised electrons.
- Identifies the metallic bond as the electrostatic attraction between positive ions and delocalised electrons.
- Links delocalised electrons to electrical or thermal conductivity.
- Links strong metallic bonding to high melting and boiling points.
Examiner Tips
- 💡Sketch a small section of the regular lattice and label the repeating pattern.
- 💡Use the words giant, regular and lattice in your answer to show precise vocabulary.
- 💡When asked to explain a property, begin from the structure and strong metallic bonds, then link to the behaviour.
- 💡Use the phrase sea of delocalised electrons when describing the model.
- 💡Always name the two charged species involved in the metallic bond before explaining the attraction.
- 💡When explaining conductivity, state that the delocalised electrons carry charge or energy through the metal.
Common Mistakes
- Saying that metals are made of molecules; correct this by describing a giant lattice of atoms.
- Describing the arrangement as random; correct this by stating that the atoms are in a regular pattern.
- Confusing giant structures with simple molecular structures; correct this by noting that the lattice has no fixed small number of atoms.
- Saying that metal atoms share pairs of electrons in the same way as covalent bonds; correct this by describing delocalised electrons shared across the whole lattice.
- Describing the metal as negative ions; correct this by stating that the lattice contains positive metal ions.
- Claiming that the delocalised electrons are fixed in place; correct this by stating that they are free to move throughout the structure.