Diamond has a regular tetrahedral geometry. This is because each carbon is connected to four neighbouring carbon atoms via single covalent bonds, resulting in a single unit of a crystal. These crystal units lie in different planes and are connected to each other, resulting in a rigid three-dimensional cubic pattern of the diamond.
Diamond:
- Has a high density of 3.5g/cc.
- Has a very high refractive index of 2.5.
- Is a good conductor of heat.
- Is a poor conductor of electricity.
Graphite
In graphite, each carbon atom is bonded covalently to three other carbon atoms, leaving each carbon atom with one free valency. This arrangement results in hexagonal rings in a single plane and such rings are stacked over each other through weak Van der Waals forces.
Graphite:
- Has a density of 2.25 g/cc.
- Has a soft and slippery feel.
- Is a good conductor of electricity.
C60
C60, also known as Buckminsterfullerene, is the very popular and stable form of the known fullerenes.
It is the most common naturally occurring fullerene and can be found in small quantities in soot.
It consists of 60 carbon atoms arranged in 12 pentagons and 20 hexagons, like in a soccer ball.