- Also called:
- plumbago or black lead
- Key People:
- Edward Goodrich Acheson
- Joseph Dixon
- Related Topics:
- carbon
- graphene
- native element
- cliftonite
- allotrope
graphite
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What is graphite?
Graphite is a mineral form of carbon. It consists of carbon atoms arranged in widely spaced horizontal sheets of hexagonal rings. Graphite is dark gray to black, opaque, very soft, and feels greasy, which explains its name, derived from the Greek word graphein, meaning "to write." Because the layers of carbon atoms are not tightly bound, it is very soft and an excellent conductor of heat and electricity.
Graphite is formed through the metamorphosis of carbonaceous sediments, the reaction of carbon compounds with hydrothermal solutions or magmatic fluids, or the crystallization of magmatic carbon. Natural graphite is divided into amorphous, flake, and vein types.
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How is graphite related to carbon?
Graphite is a mineral form of carbon. It consists of carbon atoms arranged in layers of hexagonal rings. These layers are loosely held together, making graphite soft and giving it a greasy feel.
Graphite and diamond are allotropes, or crystalline forms, of carbon. Graphite is dark gray to black, opaque, and soft, whereas diamond can be colorless and transparent and is the hardest naturally occurring substance. Graphite is an excellent conductor of heat and electricity, while diamond is an insulator.
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What are the main properties of graphite?
Graphite, a mineral form of carbon, is known for its unique properties stemming from its layered structure of carbon atoms arranged in hexagonal sheets.
Key properties include:
* Structure Graphite has a layered structure of carbon atoms in hexagonal rings.
* Feel Graphite has a greasy feel.
* Marking Graphite leaves a black mark.
* Softness Graphite is very soft due to weak bonds between carbon layers.
* Conductivity Graphite is an excellent conductor of heat and electricity.
* Types Graphite occurs naturally in amorphous, flake, and vein forms.
* Other The layers of carbon in graphite are called graphene.3 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
How is graphite used in everyday life?
Graphite, a mineral form of carbon, is known for its diverse applications in everyday life. Its unique layered structure makes it an excellent conductor of heat and electricity.
Graphite is a key component in pencil lead, lubricants, and brushes for electric motors. It is also used in steelmaking, where it is used as electrodes in electric arc furnaces. In addition, graphite is used as the anode in lithium-ion batteries for electric vehicles. Because it can withstand extreme loads and temperatures, graphite is also used as a solid lubricant.
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What does the atomic structure of graphite look like?
Graphite's crystal structure features carbon atoms arranged in parallel layers. Within each layer, carbon atoms form fused hexagonal rings that extend infinitely in two dimensions. The carbon-carbon bond distance within a layer measures 1.42 × 10^-8 cm, falling between single and double bond distances.
The stacking pattern of the layers follows an ABABA... sequence, where each layer separates two identically oriented layers. The interlayer distance, 3.37 × 10^-8 cm, is large enough to prevent localized bonding between layers; bonding between layers likely occurs through van der Waals interactions.
The individual layers of carbon in graphite are called graphene, which was successfully isolated in single-layer form in 2004.
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How is graphite different from other forms of carbon, like diamond?
Graphite and diamond are allotropes, or crystalline forms, of carbon, but they differ significantly in structure and properties.
In graphite, carbon atoms arrange in widely spaced horizontal sheets of hexagonal rings, crystallizing in the hexagonal system. The carbon-carbon bond distance within each layer is 1.42 × 10^-8 cm. Graphite is soft and has a greasy feel because the layers are not tightly bound. It is also an excellent conductor of heat and electricity.
In contrast, diamond has a crystal structure characterized by a three-dimensional array of carbon atoms, where each carbon atom is covalently bonded to four others in a tetrahedral arrangement. Diamond crystallizes in the octahedral or tetrahedral system. The distance between carbon atoms along the bond is 1.54 × 10^-8 cm. This compact, strongly bonded structure makes diamond the hardest naturally occurring substance with exceptional brilliance.
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graphite, mineral consisting of carbon. Graphite has a greasy feel and leaves a black mark, thus the name from the Greek verb graphein, “to write.”
Graphite has a layered structure that consists of rings of six carbon atoms arranged in widely spaced horizontal sheets. Graphite thus crystallizes in the hexagonal system, in contrast to diamond, another form of carbon, that crystallizes in the octahedral or tetrahedral system. Such pairs of differing forms of the same element usually are rather similar in their physical properties, but not so in this case. Graphite is dark gray to black, opaque, and very soft (with a Mohs scale hardness of 1.5), while diamond may be colorless and transparent and is the hardest naturally occurring substance (with a Mohs scale hardness of 10). Graphite is very soft because the individual layers of carbon atoms are not as tightly bound together as the atoms within the layer. It is an excellent conductor of heat and electricity. For detailed physical properties of graphite, see native element (table).
Before the discovery in 1779 that graphite when burned in air forms carbon dioxide, graphite was confused with both the metal lead and a superficially similar substance, the mineral molybdenite.
Graphite is formed by the metamorphosis of sediments containing carbonaceous material, by the reaction of carbon compounds with hydrothermal solutions or magmatic fluids, or possibly by the crystallization of magmatic carbon. It occurs as isolated scales, large masses, or veins in older crystalline rocks, gneiss, schist, quartzite, and marble and also in granites, pegmatites, and carbonaceous clay slates. Small isometric crystals of graphitic carbon (possibly pseudomorphs after diamond) found in meteoritic iron are called cliftonite.
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Naturally occurring graphite is classified into three types: amorphous, flake, and vein. Amorphous is the most common kind and is formed by metamorphism under low pressures and temperatures. It is found in coal and shale and has the lowest carbon content, typically 70 to 90 percent, of the three types. Flake graphite appears in flat layers and is formed by metamorphism under high pressures and temperatures. It is the most commonly used type and has a carbon content between 85 and 98 percent. Vein graphite is the rarest form and is likely formed when carbon compounds react with hydrothermal solutions or magmatic fluids. Vein graphite can have a purity greater than 99 percent and is commercially mined only in Sri Lanka.
Graphite was first synthesized accidentally by Edward G. Acheson while he was performing high-temperature experiments on carborundum. He found that at about 4,150 °C (7,500 °F) the silicon in the carborundum vaporized, leaving the carbon behind in graphitic form. Acheson was granted a patent for graphite manufacture in 1896, and commercial production started in 1897. Since 1918 petroleum coke, small and imperfect graphite crystals surrounded by organic compounds, has been the major raw material in the production of 99 to 99.5 percent pure graphite.
Graphite is used in pencils, lubricants, crucibles, foundry facings, polishes, brushes for electric motors, and cores of nuclear reactors. Its high thermal and electrical conductivity make it a key part of steelmaking, where it is used as electrodes in electric arc furnaces. In the early 21st century, global demand for graphite has increased because of its use as the anode in lithium-ion batteries for electric vehicles. About 75 percent of graphite is mined in China, with significant amounts mined in Madagascar, Mozambique, and Brazil.