Summary
Giant covalent structures are large networks of atoms bonded by covalent bonds, resulting in unique properties.
- Diamond — a form of carbon where each atom is bonded to four others, making it very hard and with a high melting point. Example: Used in cutting tools due to its hardness.
- Graphite — a form of carbon where each atom is bonded to three others, forming layers that can slide over each other. Example: Used as a lubricant and in electrodes because it conducts electricity.
- Silicon(IV) oxide (SiO2) — a compound where each silicon atom is bonded to four oxygen atoms, forming a structure similar to diamond. Example: Found in quartz, a mineral in sand.
Exam Tips
Key Definitions to Remember
- Giant covalent structure: A large network of atoms bonded by covalent bonds.
- Allotropes: Different forms of the same element with different structures.
Common Confusions
- Confusing hardness with strength; diamond is hard but brittle.
- Mistaking pencil lead for metal lead; pencil lead is actually graphite.
Typical Exam Questions
- What is the structure of diamond? Each carbon atom is bonded to four others, forming a rigid lattice.
- How does graphite conduct electricity? It has delocalized electrons that can move between layers.
- What is the similarity between diamond and silicon(IV) oxide? Both have a giant covalent structure.
What Examiners Usually Test
- Differences in properties and uses of diamond and graphite.
- The structure and bonding in silicon(IV) oxide compared to diamond.