Carbon: The 4th most abundant element in the Universe after Hydrogen, Helium and Oxygen. It is found in abundance in the Sun, stars, comets, and atmospheres of most planets. The atmosphere of Mars, for example, contains 96% CO2. It is the chemical basis for all known life and is found in many different compounds. It is in the food you eat, the clothes you wear, the cosmetics you use and the petrol that fuels your car.
A Group 14 element, Carbon is found free in nature in three allotropic forms: amorphous (irregularly shaped), graphite, and diamond. The differences in their structure are profound. Diamond crystalises in a cubic system, whereas graphite does so in a hexagonal, layered system. As a result, graphite is one of the softest known materials while diamond is one of the hardest.
Carbon, as microscopic diamonds, is found in some meteorites. Natural diamonds are found in ancient volcanic “pipes” such as found in South Africa.
More recently, another form of carbon, buckminsterfullerene, C60, has been discovered. This new form of carbon is the subject of great interest in research laboratories today.
Carbon is present as carbon dioxide in the atmosphere and dissolved in all natural waters. It is a component of rocks as carbonates of calcium (limestone), magnesium, and iron. Coal, petroleum, and natural gas are chiefly hydrocarbons. Carbon is unique among the elements in the vast number of variety of compounds it can form.