Diamond, Graphite, the Fullerenes, and Nanotechnology

Graphite has an entirely different structure. It has a layer structure, with each layer being attracted to one another by London forces. Within a layer, each carbon atom is covalently bonded to three other atoms, giving a flat layer of carbon-atom hexagons. Here is the resonance formula for a portion of a layer of graphite  

The bonding is sp with delocalized tt bonds. As a result of the delocalized bonding, graphite is an electrical conductor, unlike diamond, which is an insulator. 

In 1985, Richard Smalley and Robert Curl of the United States and Harold Kroto of the United Kingdom discovered the first of a series of molecular forms of the element carbon Cso, which they called buckminsterfullerene or, more casually, buckyball. (See the essay at the end of this section.) Since then, scientists have discovered a series of related carbon-atom molecules, calAsA fullerenes. Buckminsterfullerene has a soccer-baU shape, with carbon atoms enclosing a hollow space. Other fullerenes have tube shapes. 

The diamonds (right) were made by heating graphite (left) under high pressure with a catalyst. Pencil lead is graphite mixed with clay. 

Diamond-film preparation by chemical vapor deposition (CVD) 

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Carbon is the basis of all life on earth, and without a doubt, one of the most versatile elements known to man. More than ten million carbon compounds are known today, many times more than that of any other element. Carbon itself exists in several allotropes. Its flexible electron configuration allows carbon to form three hybridization states which lead to different types of covalent bonding. The most representative macroscopic forms of carbon are graphite and diamond. In 1985, Kroto et al. discovered a third carbon allotrope, the fullerenes. While their experiments aimed at understanding the mechanisms by which long chained carbon molecules are formed in interstellar space, their results opened a new era in science - the beginning of nanotechnology. 

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