Diamond and graphite
Same carbon, different structures.
Hard and slippery
Diamond is the hardest substance known. Graphite is smooth and slippery. Both are formed only by carbon atoms.
What makes two forms of the same element so different?
What this lesson covers
The idea
In diamond each carbon bonds to four others in a rigid 3-D structure; in graphite each bonds to three others in stacked hexagonal layers; so diamond is hardest and graphite slippery and conducting, though their chemical properties are the same.
Hard and slippery
Diamond is the hardest substance known. Graphite is smooth and slippery. Both are formed only by carbon atoms.
What makes two forms of the same element so different?
- The manner in which the carbon atoms are bonded to one another
- One of them has atoms of a different element mixed in
- The carbon atoms in one are a different kind of carbon
Inside the two forms
Open every tab.
Structure explains properties
The atoms are the same. Only the way they are joined is different, and that changes the physical properties.
In diamond each carbon bonds to four others in a rigid 3-D structure. In graphite each bonds to three others in stacked hexagonal layers. So diamond is the hardest and graphite is slippery and a conductor, though their chemical properties are the same.
- Diamond | Graphite
- Bonded to | 4 other carbon atoms | 3 other carbon atoms
- Structure | rigid 3-D | stacked hexagonal layers
- Physical property | hardest substance known | smooth, slippery, very good conductor
Notes
In diamond each carbon bonds to four others in a rigid 3-D structure; in graphite each bonds to three others in stacked hexagonal layers. Diamond is hardest, graphite slippery and conducting, but their chemical properties are the same.
Check yourself
To how many other carbon atoms is each carbon atom bonded in graphite?
Answer: 3
Each carbon atom in graphite is bonded to three others in the same plane.
Which form of carbon is the hardest substance known?
Which form of carbon is a very good conductor of electricity?
How do the chemical properties of diamond and graphite compare?
- Diamond — correct. Yes!
- Graphite. Graphite is smooth and slippery.
- Both are equally hard. Diamond is the hardest substance known, while graphite is smooth and slippery.
- Diamond. The book names graphite as the very good conductor of electricity.
- Graphite — correct. Yes!
- Neither. Graphite is a very good conductor of electricity, unlike other non-metals.
- They are very different. The physical properties are very different. The chemical properties are the same.
- Diamond reacts but graphite does not. Their chemical properties are the same, since both are formed only by carbon atoms.
- They are the same — correct. Yes!