# Aluminium is a metal widely used in overhead power cables and aircraft frames. Explain, in terms of metallic bonding, why aluminium is a good electrical conductor and why it has a high melting point.

> Edexcel A-Level Chemistry (9CH0) — 2.3 Metallic bonding · Explain · 5 marks

> Aluminium is a silvery-white metal. It is lightweight yet strong, and is chosen for electrical cables because it conducts electricity well. It has a melting point of 660 °C.

## Mark scheme (5 marks)

1. Aluminium atoms lose their outer electrons to form positive ions (cations)
2. The released electrons form a 'sea' of delocalised electrons that can move freely throughout the structure
3. When a voltage is applied, the delocalised electrons can move towards the positive terminal, allowing charge (current) to flow
4. There are strong electrostatic forces of attraction between the positive ions and the delocalised electrons
5. A large amount of energy is needed to overcome these strong attractions, which is why aluminium has a high melting point

## Key terms

- [metallic bonding](https://www.gradenine.co.uk/glossary/metallic-bonding)
- [electrical conductor](https://www.gradenine.co.uk/glossary/electrical-conductor)

## Related

- [Revision notes for Edexcel A-Level Chemistry (9CH0)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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