The Many Forms of Carbon
The forms of carbon and how each structure gives its properties: diamond, graphite, graphene and the fullerenes, and why graphite conducts while diamond is hard.
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One element, many forms
Diamond and the graphite in a pencil are both made of nothing but carbon, yet one is the hardest natural material and the other is soft enough to write with. The difference is how the carbon atoms are joined. This module looks at the forms of carbon and how the structure of each one explains what it can do.
Carbon vocabulary
Learn these four forms before you study their properties.
Diamond against graphite
Two forms of carbon behave very differently.
Read the structure first
A top answer works from the structure to the property. Count how many bonds each carbon atom makes, and work out what that leaves free to move or lets the atoms do. For graphene and the cage or tube forms, tie the shape directly to a real use. Never state a property without the structure that causes it.
Match the property
- diamond
- graphite
- graphene
- fullerene
- very hard and does not conduct
- soft and slippery, and conducts
- one atom thick, strong and conducts
- a hollow cage or tube
Match the use
- diamond in a drill tip
- graphite in a pencil
- graphene in electronics
- a fullerene cage
- cutting hard materials because it is hard
- writing and lubricating because layers slide
- carrying current because it conducts
- carrying a drug molecule inside it
Why does graphite conduct?
Why is graphite able to conduct electricity?
- Each carbon forms three bonds, leaving one electron free to move.
- Each carbon forms four bonds with no spare electrons.
- It contains ions that move.
- It is a metal.
About diamond
Select the TWO statements that are true of diamond.
- Each carbon is bonded to four others.
- It is very hard.
- It conducts electricity well.
- It is soft and slippery.
Order the reasoning
Put the steps of explaining a property of carbon in order, earliest first.
- Name the form of carbon
- Count the bonds each carbon makes
- Describe the structure this gives
- Explain the property that results
Complete the facts
In diamond each carbon is bonded to _____ others, making it very hard. In graphite each carbon is bonded to _____ others, leaving one electron free to move so it can _____. A single layer of graphite is called _____. A hollow cage or tube of carbon is a _____.
Bonds and free electrons
In diamond each carbon makes 4 bonds; in graphite each carbon makes 3. Subtract 3 from 4 to find how many electrons each graphite carbon leaves free to move. What is the answer?
Spot the conductors
Tap the TWO forms of carbon that conduct electricity.
- graphite
- graphene
- diamond
- diamond in a drill tip
Choose the form
Read what is needed and choose the best form of carbon.
- A tool is needed to cut through very hard rock. Which form of carbon suits this?
- A pencil needs to leave a mark and slide smoothly on paper. Which form suits this?
- A very thin, strong material that conducts is needed for electronics. Which form suits this?
Explain the forms
Explain how the structure of diamond and graphite gives each its properties.
- Describe the bonding in diamond and why it is hard
- Describe the bonding in graphite and why it conducts and is soft
- Give one use of graphene or a fullerene linked to its structure