Radioisotope dating fossils
Whereas graphite is in the form of sheets, a diamond is basically a huge "molecule" composed of carbon atoms strung together by covalent bonds.The size of this "molecule" corresponds to the size of the diamond: a diamond of 1 carat, for instance, contains about 10 (10,000,000,000,000,000,000,000 or 10 billion billion) carbon atoms.We have stated that carbon forms tetravalent bonds, and makes multiple bonds with a single atom.In addition, we have mentioned the fact that carbon forms long chains of atoms and varieties of shapes. These are good questions, but not ones we will attempt to answer here.Nonetheless, people still use the word "lead" in reference to pencils, much as they still refer to a galvanized steel roof with a zinc coating as a "tin roof." In graphite the atoms of each "sheet" are tightly bonded in a hexagonal, or six-sided, pattern, but the attractions between the sheets are not very strong.This makes it highly useful as a lubricant for locks, where oil would tend to be messy.
This is not surprising, considering that pencil "lead" is, in fact, a mixture of graphite, clay, and wax.Graphite is essentially a series of one-atom-thick sheets of carbon, bonded together in a hexagonal pattern, but with only very weak attractions between adjacent sheets.A piece of graphite is thus like a big, thick stack of carbon paper: on the one hand, the stack is heavy, but the sheets are likely to slide against one another.In fact, what Wöhler had glimpsed—and what other scientists who followed came to understand, was this: what separates the organic from the inorganic is the manner in which the carbon chains are arranged.Ammonium cyanate and urea have exactly the same numbers and proportions of atoms, yet they are different compounds.