Answer to Question #25115 in Organic Chemistry for ganesh

Question

what are the allotrophy forms of carbon. did they occur naturally or prepared artificially.

Answer 1

Carbon is capable of forming many allotropes due to its valency.There are two main Allotropic Forms of Carbon. They are the following and they occur naturally:
Diamond and Graphite.
Diamond: The Diamond is hardest known substance (or Natural Substance). It is in Crystalline state. It's density is 3.51 gram per cubic centimeter. It's Melting Point is 3500 centigrade. It has high refractive index i-e: 2.45. It is a bad conductor of electricity. Pure Diamond is transparent to X-rays that's why we use X-rays to distinguish between real diamond & imitation diamond. It's structure is Tetrahedral structure.
A single layer of graphite is called graphene and has extraordinary electrical, thermal, and physical properties. It can be produced by epitaxy on an insulating or conducting substrate or by mechanical exfoliation (repeated peeling) from graphite.
Amorphous carbon is the name used for carbon that does not have any crystalline structure. As with all glassy materials, some short-range order can be observed, but there is no long-range pattern of atomic positions. While entirely amorphous carbon can be produced, most amorphous carbon actually contains microscopic crystals of graphite-like,or even diamond-like carbon.Coal and soot or carbon black are informally called amorphous carbon. However, they are products of pyrolysis.
Carbon allotropes which were prepared are next:
The buckminsterfullerenes, or usually just fullerenes or buckyballs.
Carbon nanotubes, also called buckytubes, are cylindrical carbon molecules with novel properties that make them potentially useful in a wide variety of applications.
Carbon nanobuds are a newly discovered allotrope of carbon in which fullerene like "buds" are covalently attached to the outer sidewalls of the carbon nanotubes.
Glassy carbon or vitreous carbon is a class of non-graphitizing carbon widely used as an electrode material in electrochemistry, as well as for high temperature crucibles and as a component of some prosthetic devices.
There are some other allotropes which were prepared:
Carbon nanofoam
Carbide-derived Carbon
Lonsdaleite (hexagonal diamond)
Linear acetylenic carbon