GCSE Chemistry Metallic Bonding Notes
In a metal, positive ions sit in a sea of delocalised electrons. This bonding explains why metals conduct, bend and have high melting points.
Key concepts
- Metallic bond
- Strong electrostatic attraction between positive metal ions and delocalised electrons.
- Delocalised electrons
- Outer electrons that are free to move throughout the whole metal structure.
- Alloy
- A mixture of a metal with other elements. Different-sized atoms disrupt the layers, making alloys harder than pure metals.
- Metals conduct electricity and heat because delocalised electrons carry charge and energy.
- Metals are malleable because layers of ions can slide past each other.
- Alloys such as steel and brass are harder than the pure metals they are made from.
Worked example
Explain why copper is a good electrical conductor and is malleable.
- 1Copper has a metallic structure with delocalised electrons that can move.
- 2The moving electrons carry electrical charge, so copper conducts.
- 3The layers of positive ions can slide over each other without breaking the metallic bonds.
- 4This lets copper change shape without shattering, so it is malleable.
Answer: Delocalised electrons carry current; sliding layers of ions make copper malleable.
Common mistakes
✗ Saying protons carry the charge in metallic conduction.
✓ The delocalised electrons move and carry the current.
✗ Describing alloys as compounds.
✓ Alloys are mixtures, not chemically bonded compounds.
✗ Forgetting to mention 'sliding layers' when explaining malleability.
✓ Layers of ions slide past each other; this is why metals bend.
Quick check
Try these, then reveal the answers.
Why do metals conduct electricity?Reveal answer
Delocalised electrons are free to move and carry charge.
Why are alloys harder than pure metals?Reveal answer
Different-sized atoms distort the layers so they cannot slide easily.
What holds a metallic lattice together?Reveal answer
Strong electrostatic attraction between metal ions and delocalised electrons.
Exam tips
- Use the exact phrase 'sea of delocalised electrons' to secure the mark.
- Link malleability to sliding layers, not to bond strength.
- For alloys, say the different-sized atoms 'distort the layers' preventing sliding.
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Frequently asked questions
What is metallic bonding?+
The strong attraction between positive metal ions and a shared sea of delocalised electrons that holds a metal together.
Why are alloys harder than pure metals?+
The different-sized atoms in an alloy disrupt the regular layers of ions so they cannot slide over each other easily.
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