No other element, except for hydrogen, occurs in even a fraction of that number of compounds.As an element, carbon occurs in a striking variety of forms.Coal, soot, and diamonds are all nearly pure forms of carbon.Carbon also occurs in a form, discovered only recently, known as fullerenes or buckyballs.Its density is about 1.5 to 1.8 grams per cubic centimeter.The numerical value for these properties varies depending on where the graphite originates., that is formed during respiration, combustion, and organic decomposition, is an essential component in photosynthesis, and is used in food refrigeration, carbonated beverages, inert atmospheres, fire extinguishers, and aerosols. (Elements & Compounds) a colourless odourless incombustible gas present in the atmosphere and formed during respiration, the decomposition and combustion of organic compounds, and in the reaction of acids with carbonates: used in carbonated drinks, fire extinguishers, and as dry ice for refrigeration. Also called: carbonic-acid gas , that is present in the atmosphere and is formed when any fuel containing carbon is burned.It is breathed out of an animal's lungs during respiration, produced by the decay of organic matter, and used by plants in photosynthesis.

It occurs in more different forms than any other element in the periodic table.

Buckyball carbon holds the promise for opening a whole new field of chemistry (see accompanying sidebar).

Carbon occurs extensively in all living organisms as proteins, fats, carbohydrates (sugars and starches), and nucleic acids.

Among the non-crystalline allotropes of carbon are coal, lampblack, charcoal, carbon black, and coke. Coke is nearly pure carbon formed when coal is heated in the absence of air.

Carbon allotropes that lack crystalline structure are amorphous, or without crystalline shape.