Question 1
Why is SiO₂ a giant structure rather than a simple molecule?
Need a hint for Question 1?
Look for a continuous network of bonds.
Check Question 1
Its covalent bonds extend through a continuous network, not separate SiO₂ molecules.
STUDENT SPACE · TOPIC 7
Giant covalent structures and metals
Relate bonding and structure to the properties and uses of diamond, graphite, silica and metals.
The essentials
- Diamond has four covalent bonds per carbon in a giant network. Graphite has three per carbon in layers.
- Graphite layers can slide because the forces between layers are weak. Delocalised electrons carry charge along the layers.
- SiO₂ has a giant covalent network. Metals contain positive ions attracted to delocalised electrons, which carry charge. Metal ion layers can slide while attraction remains.
Key vocabulary
| English | Chinese |
|---|---|
| giant covalent | 巨型共价结构 |
| delocalised electron | 离域电子 |
| malleable | 可锻的 |
Quick practice
Try each question before opening its hint or answer. Use paper for calculations and diagrams.
Question 2
Explain why graphite is useful as both a lubricant and an electrode.
Need a hint for Question 2?
Explain sliding layers and mobile electrons separately.
Check Question 2
Layers slide because forces between them are weak. Delocalised electrons carry charge.
Question 3
Explain why a metal conducts electricity and can change shape without shattering.
Need a hint for Question 3?
Metallic attraction persists when layers change position.
Check Question 3
Delocalised electrons move and carry charge. Layers of ions slide while metallic attraction remains.
Use the matching chapter worksheet. Attempt independently, compare your reasoning with your partner, then bring unresolved questions to your teacher.