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Carbon

Carbon

Background:


Various forms or allotropes 
of carbon. license
Various forms or allotropes
of carbon. license
Carbon is sixth element in the periodic table with an atomic weight of 12. It is commonly encountered in our lives as the black residue left by burning paper, the "lead" in our graphite pencils or the glitter of diamonds in expensive jewellery.

Less visible, but even more important, is the fact that carbon plays a role in almost every biological process required to make our lives possible. Carbon also plays a role in the creation of fuels, plastics and pharmaceuticals, which we use to make our lives safe, comfortable and entertaining.

As if the above were not enough, carbon is an important catlyst to the nuclear fusion process in stars that are as little as 10% bigger than our sun. Even for our sun, 2% of the energy we enjoy comes from a carbon catalysed nuclear fusion process.

Physical Properties:


Formula/Symbol: C
Classification: non-metal
Melting Point: 3500.0 C
Boiling Point: 4827.0 C
Color: usually black but it can be clear and colorless in diamond form
Density: 2.267 g / cm-3 (graphite form)
3.513 g/cm-3 (diamond form)

According to the Wikipedia pure carbon is encountered in eleven different forms or allotropes. All forms of carbon are solid at room temperature, are relatively resistant to chemical corrosion and they all burn to form CO and CO2 when heated to high temperatures in the presence of oxygen.

The difference between these forms can be subtle and in our everyday experience we encounter them mainly in one of three important forms:
  • graphite
  • diamond
  • lamp black

Diamond

Diamond is one of the hardest materials in the world and ranks a 10 on Mohs scale of hardness for minerals. In its pure form it is clear and colorless.

Graphite

Commonly seen as the "lead" in lead pencils. Graphite is so soft that we have used its propencity to 'rub off', to make writing instruments since the middle of the 16th century.

Lamp Black

Lamp black is a fine powder left behind by the burning of a flame. It is extremely black and is used to absorb light in situations where the absorbtion of the light must be as complete as possible as well as independent the light frequency.

Buckey Balls and Nanotubes

During the past 25 years we have discovered that carbon can for hollow structures similar to geodesic domes referred to informally as "Bucky Balls". In fact carbon atoms can form not only domes but also tubes, which when used as fibres they have the potential to help us create composite materials with strength to weight ratios which far exceed steel. An important potential application for this material could be the development of a "space elevator".

Chemical Properties:


As unique and interesting as carbon is in its pure form, the real magic of carbon comes from its ability to serve as connecting block in a chemical Mechano Set that we refer to as "Organic Chemisty".

As the name implies, Organic Chemistry is the chemistry of life. But it is also the chemistry required to produce fuels, solvents, plastics, dies, pharmaceuticals and much more.

One of the properties that makes Carbon unique is its ability to create four covalent bonds allowing it to link to itself in order to create carbon chains of various lengths and configurations, or to connect to non-carbon atoms in order to form compounds with unique and specialized chemical properties.

Hydrogen plays a special role in carbon chemistry as an "end adapter" ... Wherever a Carbon atom connects to a hydrogen atom the carbon chain ends. This special relationship between carbon and hydrogen is so important that it leads to study of a class of chemicals knowns as "Hydrocarbons" which consist of combinations of only Hydrogen and Carbon atoms.

Uses and Applications:


Carbon in its various forms has a myriad of uses, a few of which include:
  • Activated carbon is used in filters for water purification;
  • Graphite is mixed with clay to form the "lead" in lead pencils;
  • Diamonds are used for jewellery; for cutting tools and as abrassive for use in mechanical grinding and in mining;
  • Carbon black or "soot" is used as a light absorbtion material;
  • Carbon in the form of coal is used as a fuel for heating and for the production of mechanical energy for manufacturing, transportation and the generation of electicity;
  • Hydro Carbons are derived primarliy from fossil based crude oil, they are refined from their raw form for use as fuels and lubricants; and as the base for the manufacture of organic chemicals used in the plastic and pharmacutical industries.
  • Graphite powder is used in machinery as a dry lubricant;
  • Carbon Dating is a technique used to estimate the approximate time at which the carbon contained in archeological relic was extracted from atmospheric C02.
  • Solid carbon or "coke" is used as a reduction agent to refine metals from their ores.

Important Compounds and Derivatives:


Carbon oxidizes to either carbon dioxide CO2 or carbon monoxide CO, by burning in the plentiful, or limited, presence of oxygen respectively.

CO2 and CO are quite reactive especially when mixed with water. Starting from either of these forms, or from crude oil or organic oil hydrocarbon chains, literally thousands of carbon based compounds can be derived.

Laboratory Preparation:


Carbon black or "soot" can be obtained by holding a glass slide or glass container over an open burning flame such as a candle or Bunsen Burner.

Industrial Preparation:


Carbon black is manufactured on an industrial scale by burning crude oil in an restricted air flow environment. Carbon particles are collected on, and recovered from cloth or paper filters.

Carbon can be recovered from coal or wood by heating these materials in the absence of air in order to drive of volatile materials and leave behind raw carbon, also referred to as "coke".

Industrial grade diamonds can be manufactured by subjecting other forms of carbon to high pressure and temperaures over extended periods of time.

Naming Conventions:


Carbon in its various forms can be referred to as:
  • soot;
  • diamond;
  • graphite;
  • coke;
  • Buckey Balls;
  • carbon nanotubes;
  • Fullerenes;
Carbon compounds are named according to IUPAC system of nomenclature or according to common names derived from the early use and derivation of specific organic chemicals.

History:


Carbon was likely first discovered as charcoal in prehistoric times as a residual from the incomplete combustion of wood and other plant matter. It's prehistoric use in the smelting of ores made possible both the Bronze Age and later the Iron Age. The element's name is derived from the Latin name "carbo" for burnt wood.

Until modern times carbon was confused with other minerals of similar appearance, for example molydenite (MoS2) and lead.
By 1779 graphite was still thought to be a form of lead, when Carl Wilhelm Scheele showed that graphite produces the same amount of carbon dioxide gas per gram as amorphous carbon does. The name graphite, was assigned to the material by A. G. Werner in 1789 deriving it from the Greek 'ypa4ew, " to write, because of the fact that the mineral was, and is still, used to make pencils

In 1789, Antoine Lavoisier's listed carbon as an "oxidizable and acidifiable nonmetallic element" in his early chemistry textbook Trait Elementaire de Chimie. In 1772 he showed that diamonds are a form of carbon. He did this by burning and carefully weighing both diamond and carbon samples in order to show that both produced no water vapor and the same amount of carbon dioxide gas per gram. .

In 1985 a new form of carbon was discovered by Harold Kroto (Sussex University), Robert Curl, Jr. (Rice University), and Richard Smalley (Rice University). The new form was called "buckministerfullerene" because its molecules resemble the geodesic domes designed by architect Buckminister Fuller for the 1967 World's fair. "Buckyballs" are being considered in the design of next-generation lubricants, drug delivery systems, industrial catalysts, and nanoscale machinery.

Bibliography:


Wikipedia entry on Carbon
History of the lead pencil.
Wikipedia article on Fullerenes or "Buckey Balls" and Carbon Nanotubes
1911 Britanica article on Graphite
Visualizations for Diamond, Graphite and Fullerine structures
An article describing carbon catalysis of nuclear fusion.

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