# Tungsten is a metal used to make the filaments of incandescent light bulbs because it has a very high melting point and can be drawn into thin wires. Tungsten has a giant metallic structure. Describe the structure of a giant metallic structure and use this structure to explain why tungsten can be drawn into thin wires without breaking.

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

> Tungsten has one of the highest melting points of any metal (3422 °C) and is used to make the thin filaments found inside incandescent light bulbs.

## Mark scheme (4 marks)

1. A giant metallic structure consists of a regular lattice of positive ions (cations)
2. Surrounded by / with a sea of delocalised electrons
3. When a force is applied, layers of positive ions can slide / move over one another
4. The delocalised electrons move with the ions, maintaining the metallic bonding / electrostatic attraction, so the structure does not break

## Key terms

- [giant metallic structure](https://www.gradenine.co.uk/glossary/giant-metallic-structure)

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