Knowledge Organiser: Metallic Bonding
Key Terms
- Metallic bond: attraction between positive metal ions and delocalised electrons
- Delocalised electrons: free electrons not fixed to any atom
- Sea of electrons: the mobile electron cloud in a metal
- Malleable: can be hammered into shape
- Ductile: can be drawn into wire
- Alloy: mixture of metals (or metal + non-metal); harder than pure metal
Must-Know Facts
- Positive metal ions surrounded by sea of delocalised electrons
- Conducts electricity — delocalised electrons carry charge
- Conducts heat — electrons transfer kinetic energy
- Malleable/ductile — layers slide, electrons maintain bond
- High MP — strong attraction between ions and electrons
- Conducts as a SOLID (unlike ionic compounds)
- Alloys harder — different-sized atoms disrupt regular layers, preventing sliding
- Steel (Fe+C), brass (Cu+Zn), bronze (Cu+Sn)
Key Equations
- No calculation equations — descriptive topic
- Metallic bond = electrostatic attraction between positive metal ions and delocalised electrons
- Conductivity: delocalised electrons move freely and carry charge/energy
Common Mistakes
- Saying metals conduct due to free ions: Metals conduct because of DELOCALISED ELECTRONS — not free ions (that is ionic compounds in solution)
- Saying pure metals are harder than alloys: Alloys are harder — different-sized atoms disrupt the regular lattice, preventing layers from sliding
- Forgetting metallic bonds are strong: Students often say metals have weak bonds — metallic bonds are actually strong, giving metals high melting points
- Saying metals are brittle: Metals are malleable and ductile because layers can slide without breaking bonds (unlike ionic compounds which are brittle)
Memory Aid
- MaDe Cm — Malleable, Ductile, Conducts (electricity and heat), high Melting point