Carbon has an electronic configuration of 2, 4. Each carbon diamond shares electrons with four other atoms of carbon - forming four single bonds.
Graphite is another carbon allotrope. It is an electrical conductor and a semi - metal, unlike diamond. Graphite is among the most stable forms of carbon allotropes under standard conditions and is used as the standard state in thermochemistry to define the heat of carbon compounds. There are three types of natural graphite:
Amorphous carbon is carbon without a crystalline structure. Although amorphous carbon can be produced, some graphite-like or diamond-like carbon microscopic crystals still exist. Amorphous carbon properties depend on the ratio of hybridized sp2 to sp3 bonds in the material. Graphite is made up purely of hybridized sp2 bonds, while diamond is made up purely of hybridized sp3 bonds. Materials high in sp3 hybridized bonds are referred to as amorphous carbon tetrahedral or carbon diamond - like.
Carbon nanomaterials constitute another allotropic carbon class. Fullerenes (also known as buckyballs) are carbon - composed molecules of varying sizes that take the form of hollow spheres, ellipsoids or tubes. Buckyballs and buckytubes are the topic of great research, as both have unique chemistry and technological applications, particularly in the fields of materials science, electronics and nanotech. Carbon nanotubes are cylindrical carbon molecules with extraordinary strength and unique electrical properties. Carbon nanobuds are recently discovered allotropes where fullerene - like "buds" are covalently attached to a carbon nanotube's outer side walls. Consequently, nanobuds have both nanotubes and fullerenes.
Glassy carbon is a non-graphitizing carbon class that is widely used in electrochemistry as an electrode material, as well as high temperature crucibles and as a component of some prothesis devices. This was first created at the General Electric Company's laboratories in the early 1960s using cellulose as the starting material. Shortly afterwards, Japanese workers found similar phenolic resin material.
Carbon nanofoam is the fifth known carbon allotrope discovered at the Australian National University in Canberra in 1997 by Andrei V. Rode and colleagues. It consists of a low-density cluster of carbon atoms in a loose three - dimensional web.
Lonsdaleite is a hexagonal allotrope of allotropic carbon diamond, thought to have been formed when meteoric graphite fell to Earth. The high heat and stress of the impact turned the graphite into a diamond, but maintained the hexagonal crystallattice of graphite.
Chemists in the United States recently reported a carbon allotrope consisting of long chains of carbon atoms with different lengths of alternative carbon bonds; and consisting of C - C bonds and C ≡ C bonds.