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Linné on line arrow Physics and the Cosmos arrow Physics and the Cosmos arrow Crystals – nature putting itself in order arrow Carbon in different forms

Carbon in different forms

As far as we know today, pure carbon can exist in three different crystalline forms. For a long time only two of them were known, namely diamond and graphite. However, in 1985 a third form, called the buckminster fulleren was discovered by Richard E. Smalley and Harry Kroto and their collaborators. Their discovery was awarded the with 1996 Nobel prize. Below you can see the crystalline structure of the three different forms of carbon. (Each ball represents one carbon atom.) By clicking on the pictures you can turn them around and study them from different directions.

 

The Buckminster fulleren

The buckminster fulleren is a molecule consisting of sixty carbon atoms (C60) ordered in the same way as the corners of a football (soccer), but the buckyball is only 7.1 Å in diameter! There are also other buckminster fullerens with smaller or larger number of carbon atoms, for example C70. The common feature of all of them is that each carbon atom is connected to three other atoms with one double bond and two single bonds. A lot of research is done in order to explore the properties of the buckminster fulleren and in trying to find applications. Here you can find some more information about the buckminster fulleren.
     
 

Diamond

Diamond is the hardest material we know of. The picture to the left shows part of the crystalline structure of a diamond, the pattern repeats itself in all directions. In a diamond each carbon atom is connected to four other atoms with single bounds. In order to create a diamond the combination of a very high pressure and temperature is required. Nowadays one can produce diamonds in industrial processes and there are lots of technical applications where one is benefiting from the properties of diamonds.
     
 

Graphite

Graphite has a special crystalline structure. As you can see in the picture to the left the atoms are ordered in separate layers. The carbon atoms in each layer are connected to each other with three bounds, one double and two single-bounds, where as the bounds between the different layers is much weaker. This means that the layers can quite easily be separated from each other and thereby graphite is a good lubricant. This property is also used in an ordinary pencil which to a large extent consists of graphite.