The Marvel That is Carbon
How can graphite and diamond be so different if they are both composed of pure carbon? A diamond is clear and hard and abrasive, while graphite is opaque and slippery. Diamond atoms are arranged as a tetrahedral, whereby each carbon attaches 3-dimensionally to three others. This accounts for its tremendous strength (diamond can scratch all other materials). In comparison, carbon atoms are arranged in layers with two kinds of bonds. Three are bonded with other carbon atoms at the corner of a hexagon, forming a 2-D chicken wire planar array. The layers then are held together weakly with the other bond. The third form of carbon, the Buckyball, was covered a while back in a Factoid, but don't expect to find one often in nature. While marveling at carbon, keep in mind that all living things are carbon-based.