Carbon Properties

Carbon heads the list of Group-IVA elements. Carbon combines very slowly with oxygen at room temperatures. At moderately high temperatures, however, carbon combines with oxygen quite readily. It can even be said that carbon becomes "oxygen hungry" at red-hot temperatures.

Most metals can be reduced from their oxides simply by heating them in the presence of carbon. Iron, for example, is reduced from iron oxide by heating it in the presence of a form of carbon known as coke.

Amorphous, graphite, and diamond

Carbon has three well-known allotropic forms: amorphous, graphite, and diamond. 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 transition to a different form.

Carbon Production

Most elemental carbon is taken directly from the earth, mostly in the form of coal, but also as natural graphite and diamonds. These natural forms are not suitable for all of the modern applications of carbon, so there have to be commercial procedures for producing the alternative forms. The production method that is used in any given instance depends largely upon the type of carbon product that is desired.
Coke, for example, is a graphite product that is about 94% carbon. Large amounts must be produced each year to meet the demands of metal refineries. It is produced by heating soft coal in an oven that has no access to outside air. This burns off most of the impurities, leaving a fairly pure form of carbon. The product is crushed into pieces between one and four inches in diameter.