It is in the food you eat, the clothes you wear, the cosmetics you use and the gasoline that fuels your car. In addition, carbon is a very special element because it plays a dominant role in the chemistry of life. Since this energy shell can hold eight electrons, each carbon atom can share electrons with up to four different atoms. Carbon can combine with other elements as well as with itself. This allows carbon to form many different compounds of varying size and shape.
Carbon alone forms the familiar substances graphite and diamond.
Both are made only of carbon atoms. Graphite is very soft and slippery. Diamond is the hardest substance known to man. The answer lies in the way the carbon atoms form bonds with each other. Notice that graphite is layered.