A piece of carbon.
The element carbon is a non-metallic material that contains six electrons. Coal, a form of carbon, has been used since prehistoric times. The name carbon comes from the Latin word carbo, which means coal. Carbon can be found in organic materials, such as plants and animals, and in inorganic materials, such as minerals and ores. Elementary carbon refers to the inorganic forms of carbon that can be found in crystalline and amorphous forms.
Crystalline forms have elementary carbon atoms arranged in a regular pattern, while carbon atoms in amorphous forms do not have regular patterns. The two crystalline forms of elemental carbon are diamonds and graphite. The crystal structure of diamond is formed by each carbon atom creating a covalent bond by sharing a pair of electrons with four other carbon atoms. Covalent bonds are the strongest chemical bonds known to mankind. Diamonds are the hardest and least volatile known substances, with a melting point of 6,242 °F (3,550 °C).
Diesel fuel creates more black carbon than gasoline.
The crystalline structure of graphite is formed by carbon atoms creating tight hexagonal bonds with other atoms in the same plane, and a looser bond between atoms in different planes. A loose bond between planes makes graphite very soft and allows graphite to be used as a lubricant. Unlike diamonds, graphite is a good electrical conductor.
Before 1955, all diamonds came from natural deposits. In 1955, laboratory testing proved that applying high pressure and temperature to graphite in the presence of a catalyst could create synthetic diamonds. Synthetic diamonds are mostly used for industrial purposes.
Amorphous carbon is created when a material containing carbon is burned without enough oxygen to allow complete combustion. The resulting carbon black can be used to create dry cell battery cores, inks, paints and is a critical element in the manufacture of rubber products. Black carbon is also the by-product of forest fires and insufficient fuel combustion in automobiles, factories, and coal-fired power generation. Diesel fuel creates more black carbon than gasoline during combustion. Black carbon can cause health and environmental problems.
A fine particulate matter that can cause health problems is amorphous elemental carbon. Asthma and chronic bronchitis have been linked to black carbon, and there is some evidence that black carbon or soot may increase the risk for emphysema and lung cancer. Black carbon is also a factor in climate change. Since black carbon remains in the atmosphere for weeks rather than the century that carbon dioxide does, decreasing black carbon emissions is seen as one of the fastest ways to possibly reduce the effects of global climate change.