# 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.

> Pearson Edexcel International GCSE Chemistry (4CH1) — 1.8 Metallic crystals · Describe and Explain · 4 marks

> Copper is widely used in electrical wiring and plumbing pipes because it can be drawn into thin wires and bent into shape without breaking.

## Mark scheme (4 marks)

1. Metals consist of a lattice of positive ions (accept: positive metal ions arranged in a regular lattice/repeating arrangement)
2. There are delocalised electrons (that move freely between/throughout the lattice)
3. When a force is applied, layers of positive ions can slide over one another
4. 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

- [lattice](https://www.gradenine.co.uk/glossary/lattice)
- [delocalised electrons](https://www.gradenine.co.uk/glossary/delocalised-electrons)
- [positive ions](https://www.gradenine.co.uk/glossary/positive-ions)

## Related

- [Revision notes for Pearson Edexcel International GCSE Chemistry (4CH1)](https://www.gradenine.co.uk/learn)
- [How to answer "Describe and Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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