Carbon can exist in different structural states known as allotropes. Two well-known allotropes are graphite, one of the softest substances, and diamond, the hardest naturally occurring mineral. Graphite has a crystalline structure in which the carbon atoms are arranged in layers of flat sheets. Each sheet consists of a network of hexagonal (six-membered) rings in which each carbon atom is bonded to three other atoms. Diamond, which is formed in the Earth at very high pressures, adopts a different crystalline structure. Each carbon atom is bonded to four others, which together form a tetrahedral shape surrounding the central carbon Diamond is transparent and hard; it acts as an excellent electrical insulator, and can be used as an abrasive. By contrast, graphite is opaque and soft. It conducts electricity, and is a good lubricant. Diamond crystallizes in the cubic system but graphite crystallizes in the hexagonal system. Carbon that lacks an overall crystalline structure is known as amorphous carbon. Although it is possible to produce carbon that is entirely amorphous (non-crystalline), material that is described as amorphous usually includes small crystals of graphite or diamond. Amorphous carbon is the main constituent of charcoal, soot (lampblack or carbon black), and activated carbon. In addition, several exotic allotropes have been synthesized or discovered, including fullerenes, carbon nanotubes, lonsdaleite, carbon nanofoam, and aggregated diamond nanorods. The carbon atoms in these allotropes have different structural arrangements. Fullerene C540. A lattice of five- and six-membered rings of carbon atoms, forming an overall spherical shape.A fullerene is composed of a sheet of carbon atoms linked together in hexagonal and pentagonal rings to take the overall form of a hollow sphere or ellipsoid. A spherical fullerene is also called a buckyball. The most well-known buckyball is Buckminsterfullerene (containing 60 carbon atoms per sphere), named after Richard Buckminster Fuller, the architect who developed the geodesic dome. A carbon nanotube likewise consists of a sheet of carbon atoms linked in hexagonal and pentagonal rings, but the overall shape is that of a hollow cylinder. Sometimes called a buckytube, it is classified as part of the fullerene family of carbon compounds. Lonsdaleite is thought to form when meteoric graphite falls to Earth. The impact\'s heat and stress transform the graphite into a structure similar to diamond, but graphite\'s hexagonal crystal lattice is retained. Also known as hexagonal diamond, lonsdaleite is transparent and brownish yellow in color. Carbon nanofoam was unexpectedly produced by scientists in Australia in 1997*. It consists of low-density clusters of carbon atoms that are bonded in six- and seven-membered rings. Surprisingly, the material is attracted to magnets and can be magnetized at temperatures below - 183°C. Aggregated diamond nanorods (ADNRs) are denser and harder than diamond, and they ap.

1. Carbon can exist in different structural states known as allotropes. Two well-known allotropes
are graphite, one of the softest substances, and diamond, the hardest naturally occurring mineral.
Graphite has a crystalline structure in which the carbon atoms are arranged in layers of flat
sheets. Each sheet consists of a network of hexagonal (six-membered) rings in which each
carbon atom is bonded to three other atoms.
Diamond, which is formed in the Earth at very high pressures, adopts a different crystalline
structure. Each carbon atom is bonded to four others, which together form a tetrahedral shape
surrounding the central carbon
Diamond is transparent and hard; it acts as an excellent electrical insulator, and can be used as
an abrasive. By contrast, graphite is opaque and soft. It conducts electricity, and is a good
lubricant. Diamond crystallizes in the cubic system but graphite crystallizes in the hexagonal
system.
Carbon that lacks an overall crystalline structure is known as amorphous carbon. Although it is
possible to produce carbon that is entirely amorphous (non-crystalline), material that is described
as amorphous usually includes small crystals of graphite or diamond. Amorphous carbon is the
main constituent of charcoal, soot (lampblack or carbon black), and activated carbon.
In addition, several exotic allotropes have been synthesized or discovered, including fullerenes,
carbon nanotubes, lonsdaleite, carbon nanofoam, and aggregated diamond nanorods. The carbon
atoms in these allotropes have different structural arrangements.
Fullerene C540. A lattice of five- and six-membered rings of carbon atoms, forming an overall
spherical shape.A fullerene is composed of a sheet of carbon atoms linked together in hexagonal
and pentagonal rings to take the overall form of a hollow sphere or ellipsoid. A spherical
fullerene is also called a buckyball. The most well-known buckyball is Buckminsterfullerene
(containing 60 carbon atoms per sphere), named after Richard Buckminster Fuller, the architect
who developed the geodesic dome.
A carbon nanotube likewise consists of a sheet of carbon atoms linked in hexagonal and

2. pentagonal rings, but the overall shape is that of a hollow cylinder. Sometimes called a
buckytube, it is classified as part of the fullerene family of carbon compounds.
Lonsdaleite is thought to form when meteoric graphite falls to Earth. The impact's heat and
stress transform the graphite into a structure similar to diamond, but graphite's hexagonal crystal
lattice is retained. Also known as hexagonal diamond, lonsdaleite is transparent and brownish
yellow in color.
Carbon nanofoam was unexpectedly produced by scientists in Australia in 1997*. It consists of
low-density clusters of carbon atoms that are bonded in six- and seven-membered rings.
Surprisingly, the material is attracted to magnets and can be magnetized at temperatures below -
183°C.
Aggregated diamond nanorods (ADNRs) are denser and harder than diamond, and they appear
to be the least compressible material known to humankind. They were produced in 2005* by
physicists in Germany who compressed carbon-60 molecules under a pressure of 20 GPa while
heating the material to 2500 K.
Solution
Carbon can exist in different structural states known as allotropes. Two well-known allotropes
are graphite, one of the softest substances, and diamond, the hardest naturally occurring mineral.
Graphite has a crystalline structure in which the carbon atoms are arranged in layers of flat
sheets. Each sheet consists of a network of hexagonal (six-membered) rings in which each
carbon atom is bonded to three other atoms.
Diamond, which is formed in the Earth at very high pressures, adopts a different crystalline
structure. Each carbon atom is bonded to four others, which together form a tetrahedral shape
surrounding the central carbon
Diamond is transparent and hard; it acts as an excellent electrical insulator, and can be used as
an abrasive. By contrast, graphite is opaque and soft. It conducts electricity, and is a good
lubricant. Diamond crystallizes in the cubic system but graphite crystallizes in the hexagonal
system.

3. Carbon that lacks an overall crystalline structure is known as amorphous carbon. Although it is
possible to produce carbon that is entirely amorphous (non-crystalline), material that is described
as amorphous usually includes small crystals of graphite or diamond. Amorphous carbon is the
main constituent of charcoal, soot (lampblack or carbon black), and activated carbon.
In addition, several exotic allotropes have been synthesized or discovered, including fullerenes,
carbon nanotubes, lonsdaleite, carbon nanofoam, and aggregated diamond nanorods. The carbon
atoms in these allotropes have different structural arrangements.
Fullerene C540. A lattice of five- and six-membered rings of carbon atoms, forming an overall
spherical shape.A fullerene is composed of a sheet of carbon atoms linked together in hexagonal
and pentagonal rings to take the overall form of a hollow sphere or ellipsoid. A spherical
fullerene is also called a buckyball. The most well-known buckyball is Buckminsterfullerene
(containing 60 carbon atoms per sphere), named after Richard Buckminster Fuller, the architect
who developed the geodesic dome.
A carbon nanotube likewise consists of a sheet of carbon atoms linked in hexagonal and
pentagonal rings, but the overall shape is that of a hollow cylinder. Sometimes called a
buckytube, it is classified as part of the fullerene family of carbon compounds.
Lonsdaleite is thought to form when meteoric graphite falls to Earth. The impact's heat and
stress transform the graphite into a structure similar to diamond, but graphite's hexagonal crystal
lattice is retained. Also known as hexagonal diamond, lonsdaleite is transparent and brownish
yellow in color.
Carbon nanofoam was unexpectedly produced by scientists in Australia in 1997*. It consists of
low-density clusters of carbon atoms that are bonded in six- and seven-membered rings.
Surprisingly, the material is attracted to magnets and can be magnetized at temperatures below -
183°C.
Aggregated diamond nanorods (ADNRs) are denser and harder than diamond, and they appear
to be the least compressible material known to humankind. They were produced in 2005* by
physicists in Germany who compressed carbon-60 molecules under a pressure of 20 GPa while
heating the material to 2500 K.