Chapter summary
Bonding and Structure, at a glance
Revisit the key comparisons, then return to any explanation you need.
O-Level 2026 SEC G3 2027. Extensions are labelled Pure only.
Bring it together
Quick revision
For every explanation: name the particles, identify the attraction, and say what can move.
| Structure and particles | Melting | Electrical conductivity |
|---|---|---|
| IonicNaClPositive and negative ions | High: strong electrostatic attractions throughout the lattice. | Solid: no. Molten or dissolved: yes, mobile ions. |
| Simple molecularMethane, iodineSeparate molecules | Generally low: weak intermolecular forces are overcome, not covalent bonds. | Pure solid or liquid: generally no mobile charged particles. |
| MacromolecularPoly(ethene)Long covalent moleculesPure only | Softens as chains move past one another; covalent backbones remain intact. | No mobile charged particles. |
| Giant covalentDiamond, graphite, SiO2Atoms in a continuous covalent networkPure only | Very high: strong covalent bonds extend through the structure. | Diamond and SiO2: no. Graphite: yes, delocalised electrons. |
| MetallicCopperPositive ions and delocalised electronsPure only | Generally high: strong attraction between ions and electrons. | Solid and molten: yes, delocalised electrons. |
Three useful corrections
Not conducting? Check whether charged particles can move, not just whether they exist.
Low melting point? Name the weak intermolecular forces, not "weak covalent bonds".
NaCl formula? It gives an ion ratio in a lattice, not a separate molecule.