Carbon
Carbon
The atoms of carbon can bond together in diverse ways, resulting in various allotropes of carbon. Well-known allotropes include graphite, diamond, amorphous carbon, and fullerenes. The physical properties of carbon vary widely with the allotropic form. For example, graphite is opaque and black, while diamond is highly transparent). Graphite is soft enough to form a streak on paper (hence its name, from the Greek verb "γράφειν" which means "to write"), while diamond is the hardest naturally occurring material known. Graphite is a good electrical conductor while diamond has a low electrical conductivity. Under normal conditions, diamond, carbon nanotubes, and graphene have the highest thermal conductivities of all known materials. All carbon allotropes are solids under normal conditions, with graphite being the most thermodynamically stable form at standard temperature and pressure. They are chemically resistant and require high temperature to react even with oxygen.
Characteristics
!Theoretically predicted phase diagram of carbon, from 1989 and updated with newer work
Characteristics
Carbon in its solid state exists in several allotropes, including graphite, a soft, black, and slippery material, and diamond, the hardest naturally occurring substance. This variation in physical properties arises from differences in atomic arrangement: graphite consists of layers of hexagonally arranged carbon atoms, while diamond features a rigid three-dimensional lattice.