Copper is a metal used to make electrical wiring. It has a giant metallic structure consisting of a lattice of positive ions surrounded by delocalised electrons. Describe the structure of a metallic crystal and explain why metals such as copper can be bent and shaped without shattering.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Copper is widely used in electrical wiring and plumbing pipes because it can be drawn into thin wires and bent into shape without breaking.
Model answer (4 marks)
Metals consist of a lattice of positive metal ions arranged in a regular repeating pattern.
Delocalised electrons move freely between and throughout the lattice.
When a force is applied, layers of positive ions can slide over one another.
The delocalised electrons continue to provide metallic bonding in the new arrangement, so the structure does not shatter.
Delocalised electrons move freely between and throughout the lattice.
When a force is applied, layers of positive ions can slide over one another.
The delocalised electrons continue to provide metallic bonding in the new arrangement, so the structure does not shatter.
Examiner tips
- Use the exact terms "lattice of positive ions" and "delocalised electrons". Show the sliding of ion layers and link it to the maintenance of metallic bonding. Keep the answer concise – one sentence per point.
Common mistakes
- Confusing delocalised electrons with ion movement. Forgetting to mention that the bonding is maintained after sliding. Using vague terms like "metallic structure" without specifying ions and electrons.
Mark scheme (4 marks)
- Metals consist of a lattice of positive ions (accept: positive metal ions arranged in a regular lattice/repeating arrangement)
- There are delocalised electrons (that move freely between/throughout the lattice)
- When a force is applied, layers of positive ions can slide over one another
- The delocalised electrons maintain the metallic bonding in the new position, so the structure does not shatter/break (accept: electrostatic attraction between positive ions and delocalised electrons is maintained after the layers slide)
Key terms in this question
lattice · delocalised electrons · positive ions
Related
- All Pearson Edexcel International GCSE Chemistry (4CH1) revision notes →
- How to answer a "Describe and Explain" question →
- Decode the mark scheme abbreviations →
More Metallic crystals questions
- Aluminium is a metal used to make aircraft frames. It has a giant metallic struc…
- Explain why metals are good conductors of electricity and have high melting poin…
- Iron is a metal with a giant metallic structure. It is used to make steel railwa…
- Tungsten is a metal used to make the filaments of incandescent light bulbs becau…