Metallic Bonding – IGCSE Chemistry Definition
IGCSE Chemistry definition of metallic bonding: positive metal ions in a sea of delocalised electrons. Covers metal properties and conductivity explanation.
Published by IGCSEChemistry.com.my
Chemistry teaching team: K. S. Tan (15+ years teaching IGCSE Chemistry) and Ms Yash (10+ years teaching IGCSE Chemistry) and Ms Kartini (15+ years teaching IGCSE Chemistry).
Mapped to Cambridge IGCSE Chemistry 0620 (2026–2028). Last updated 2026-08-19.
Metallic bonding explains the characteristic properties of metals — electrical conductivity, malleability, ductility, and high melting points. The 0620 syllabus (Supplement) requires you to describe the metallic bonding model and use it to explain metal properties. This is commonly tested alongside ionic and covalent bonding in comparison questions.
The 0620 definition
Metallic bonding is the strong electrostatic attraction between positive metal ions (cations) arranged in a regular lattice and a “sea” of delocalised electrons.
How metallic bonding works
- Metal atoms lose their outer shell electrons
- The atoms become positive ions (cations) arranged in a regular lattice
- The lost electrons become delocalised — they are free to move throughout the entire structure
- The attraction between the positive ions and the delocalised electrons holds the structure together
This is sometimes described as “positive ions in a sea of electrons.”
Explaining metal properties
| Property | Explanation using metallic bonding |
|---|---|
| Electrical conductivity | Delocalised electrons are free to move and carry charge through the metal |
| Thermal conductivity | Delocalised electrons transfer kinetic energy rapidly through the structure |
| High melting point | Strong electrostatic attraction between ions and delocalised electrons requires much energy to overcome |
| Malleable (can be hammered into shape) | Layers of ions can slide over each other without breaking the bonding — the sea of electrons adjusts to new positions |
| Ductile (can be drawn into wire) | Same reason — layers slide and the delocalised electrons maintain attraction |
| Shiny (lustrous) | Delocalised electrons interact with light, reflecting it |
Comparing the three bond types
| Feature | Ionic | Covalent | Metallic |
|---|---|---|---|
| Particles involved | Metal + non-metal ions | Non-metal atoms | Metal ions + delocalised electrons |
| What happens to electrons | Transferred | Shared | Delocalised |
| Conducts electricity (solid) | No | No (usually) | Yes |
| Melting point | High | Low (simple) or very high (giant) | High |
Worked exam question
Copper is used for electrical wiring. Use your knowledge of metallic bonding to explain why copper is suitable. (3)
Mark scheme
Copper has metallic bonding / positive ions in a sea of delocalised electrons [1]; delocalised electrons are free to move through the structure and carry charge / conduct electricity [1]; copper is ductile / can be drawn into wire because layers of ions can slide over each other without breaking the bonding [1]
Common exam mistakes
- Saying metals have “free electrons” without explaining where they come from. State that outer shell electrons are lost by the metal atoms and become delocalised.
- Confusing metallic bonding with ionic bonding. In metallic bonding, the electrons are shared across all the ions (delocalised). In ionic bonding, electrons are transferred to specific non-metal atoms.
- Explaining malleability by saying “metals are soft”. Malleability means layers of ions can slide without the structure breaking — the sea of electrons adjusts to maintain attraction.
Studying this yourself? Tutoring arrangements are normally made by a parent or guardian. Message us for the details to share with them, or send them this page.