Carbon
...ustrial diamonds used in the U.S. are now made falsely. The energy of the sun and stars can be credited at least in part to the well-known carbon-nitrogen cycle. Carbon is found free in nature in three allotropic forms: amorphous, graphite, and diamond. Carbon has four electrons in its valence shell. 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 as I discussed briefly in prior paragraphs. Both are made only of carbon atoms. Graphite is very soft and slippery. Diamond is the hardest substance known to man. They are both made of only carbon, however the atoms of carbon form bonds with each other, making them different. There are strong covalent bonds between carbon atoms in each layer. But, only weak forces exist between layers. This allows layers of carbon to slide over each other in graphite. On the other hand, in diamond eac...