Everything that you wanted to know about carbon that your folks didn't tell you Did you know that carbon is the sixth most abundant element in the cosmos, yet its abundance in the earth's crust (0.027% ) does not even make it among the top ten elements on the planet? Even so, it is widely distributed in both free (e.g. diamond and graphite) and combined states such as compounds. In fact, more compounds of carbon are known than any other element except hydrogen and oxygen. It plays a critical role on earth is its place in life forms. Every living cell, plant or animal, contains carbon. The oxides of carbon (carbon dioxide and carbon monoxide) and a number of organic compounds have a great environmental impact on our lives. Carbon exists in 7 atomic varieties known as isotopes. Carbon also has unusual physical and chemical properties . Elemental carbon, in its various forms can be found in many man-made products. Amorphous carbon (soot), diamond , graphite are all different physical forms, allotropes, that the same element can take. Unlike the allotropic forms of most other elements, the transition from one form of carbon to another is not a simple matter of changing its temperature. The allotropes of carbon are originally formed under certain conditions of raw materials, pressure, temperature, and time. Once the allotropic form is set, it is extremely difficult to force the phase transition to a different form. A phase diagram of carbon illustrates the conditions that are required to perform the transformation between the various allotropes. The physical properties of carbon depend on the allotrope of the carbon. The use of charcoal, coal, and soot have evolved since prehistoric times. Diamond has been known as a precious gem since the earliest written records. No individual can be traced to the discovery of these various carbonaceous forms. An exciting recent of a new form of carbon, Buckmister Fullerene, resulted in the awarding of a Nobel Prize in 1996. Most elemental carbon is taken directly from the earth, mostly in the form of coal, graphite, and diamonds. The industrial needs for the carbons far outstrips the availability of natural deposits, so the various natural allotropes of carbon have synthetic counterparts. The annual worldwide consumption of carbon is estimated at 1012 to 1013 kilograms.