The word carbon is derived from the Latin “carbo”, which to the Romans meant charcoal (or ember). In the modern world, carbon is, of course, much more than charcoal. From carbon come the highest strength fibers, on of the best lubricants (graphite), the strongest crystal and hardest material (diamond), and essentially non-crystalline product (vitreous carbon), on of the best gas absorbers (activated charcoal), and one of helium gas barriers. A great deal is yet to be learned and new forms of carbon are still being discovered such as the fullerene molecules and the hexagonal polytypes of diamond.
These very diverse materials, with such large differences in properties, all have the same building block—the element carbon—which is the thread that ties the various constituents of this article and gives it unity.
Carbon terminology:
The carbon terminology can be confusing because carbon is different from other elements in one important respect, which is its diversity. Unlike most elements, carbon has several material forms which are known as polymorphs (allotropes). They are composed entirely of carbon but have different physical structures and, uniquely to carbon, have different names: graphite, diamond, lonsdalite, fullerene, and others.
In order to clarify the terminology, it is necessary to define what is meant by carbon and its polymorphs. When used by itself, the term “carbon” should only mean the element. To describe a “carbon” material, the term is used with a qualifier such as carbon fiber, pyrolytic carbon, vitreous carbon, and others. These carbon materials have an sp2 atomic structure, and are essentially graphitic in nature.
Other materials with an sp3 atomic structure are, by common practice, called by the name of their allotropic form, i.t., diamond, lonsdalite, etc., and not commonly referred to as “carbon” materials, although, strictly speaking, they are.
The presently accepted definition of these words, carbon, graphite, diamond, and related terms, is given in the relevant chapters. These definitions are in accordance with the guidelines established by the international committee for characterization and terminology of carbon and regularly published in the journal carbon.
Carbon and organic chemistry:
The carbon element is the basic constituent of all organic matter and the key element of the compounds that form the huge and very complex discipline of organic chemistry. However the focus of this book is the polymorphs of carbon and not its compounds, and only those organic compounds that are used as precursors will be reviewed.