Learning focus
Develop precise chemical language, connect particle and bonding models to observations, interpret diagrams and data, and apply ideas to unfamiliar examples.
Layer structure
Each carbon atom forms three covalent bonds, creating flat layers of hexagonal rings. Strong covalent bonding acts within each layer.
Softness
Weak forces act between layers, so the layers slide over one another. Graphite is soft and slippery and is used as a lubricant.
Electrical conduction
Each carbon contributes one electron to a delocalised system. These electrons move through the layers and carry charge, so graphite conducts and can be used as an electrode.
High melting point
Melting requires breaking strong covalent bonds within the giant structure. Weak interlayer forces explain softness, not the high melting point.
Diamond comparison
Both diamond and graphite contain only carbon and are giant covalent structures. Different atom arrangements produce very different hardness and conductivity.
Practical or data skill
Build card models of graphite layers and show layer sliding. Mark the delocalised electron associated with each carbon.
Examination tip
Use two different explanations: weak interlayer forces for softness and strong covalent bonds for high melting point.
Review questions and suggested answers
Question 1
Why does graphite conduct?
Suggested answer
It has mobile delocalised electrons.
Question 2
Why is it slippery?
Suggested answer
Layers slide because forces between them are weak.
Question 3
Bonds per carbon?
Suggested answer
Three.
