Carbon

Carbon (of lat. carbo= charcoal and lat.carbonium = carbon) is a chemical element. It occurs in nature both in gediegener form and chemically bound. Due to its special Elektronenkonfiguration (halffilled L-bowl) it possesses the ability for the education ofcomplex molecules and the largest variety at chemical compounds exhibits from all chemical elements. Carbon compounds form the molecular basis of all terrestrial life.

modifications carbon

elementary carbon is non-metallic and occurs in several allotropic modifications : Diamond, graphite and Fullerene. Macroscopically the characteristics are almost diametric.
Graphite is a good electrical conductor of jet black color. the conductivity is anisotropic: very well along the crystal planes and badly perpendicularly to the levels. It is easily fissile and serves as lubricant. Diamond however is muchgood insulator and transparency. In addition diamond is the hardest well-known material and as abrasive is used. All materials on carbon basis can be attributed to these two Grundtypen (see below).

atom model of carbon

the model of the atomic andMolecule orbital illustrates, as it comes to the different development of the manifestations of carbon.

Carbon possesses six electrons. After the shell model two electrons occupy the internal 1s - bowl. The 2s - Level of the second bowl takes up likewise two electrons, twothe further 2px - and 2py - level. Only the four outside electrons of the second bowl go chemically into action. The probability density of the electrons in an s - level is spherical. In a p - level is anisotropic it. The electrons populatea drop-shaped area, in each case a drop on the left and on the right of the center along the x axis, if one imagines the atom in the center cartesian coordinate system placed. Perpendicularly to it stand py - and pz - the orbital.

diamond (FR ³) Structure

The 2s - Level can hybridize 2p level with the 3 and form 4 energetically equivalent ^FR 3 - orbital. This orbital possess an elongated, asymmetrical drop form. Goodsthe forms of the p - Orbital ones mirror-symmetrically to the center arranged, appear them now club-like in a direction extended. The picture illustrates the main lobes, the side lobes the clarity because of was let go away.
The four FR ³ - orbital are, with greatest possible distance to each othersymmetrically in the area oriented, they point to the corners of a meant tetrahedron.

If the FR 3 ^- orbital of atoms overlap themselves, they can form firm kovalente connections, which reflect then the tetrahedral structure. They form the basic structure of the diamond lattice (seeCrystal structure there.)

graphite (FR ²) structure

Only if 2 of the 3 is p - orbital at hybridizing takes part, the so-called develop. FR ²- Orbital. The FR ² - arrange themselves orbital perpendicularly to the remaining p - orbital out. For example if the p - orbital perpendicularly on the x-y plane, if the FR 2 lie ^- stands orbital symmetrically in the x-y plane. They have the same angle of 120°to each other. The picture left illustrates the situation. The unhybridisierte p - orbital is the clarity because of omitted.

FR ² - Carbon atoms can form kovalente with one another connections, which lie then in one level. Their structure is hexagonal, d.i. the essential structure of the planar levels of the Graphite (see crystal lattice structure there). The remaining p - interact to orbital likewise among themselves. They form the pi - connections with clearly smaller Binding energy as the sigma - connections of the FR ² and/or FR ³ - orbital.
Chemically we speak of a double bond. The way of writing C=C neglects the different character of both connections.
The binding energy of the diamond-like tetrahedral FR ³ - single bond “CC” is with 350 kJ/mol, those of the graphite-like hexagonal FR ² - double bond C=C only around 260 kJ/mol more highly.
In a carbon ring with six carbon atoms stabilizesitself the pi - connection by Delokalisierung of the electrons within the ring (more to it see benzene).

three-way (FR ¹) connection

if only one p - orbital with the s - orbital hybridized, result two linear arrangedConnection clubs. If we orient it along the x axis, the remaining p show - orbital in y and z-direction. Two FR-hybridized atoms can form a carbon triple bond. An example is the gas Ethin (acetylene) HC ≡ CH. During sp3-Bindungen dreidimendionale structures form andsp2 two-dimensional, form at the most linear chains for sp1-Bindungen, like for example H-C≡C-C≡c-h.

sp2 exists to manifestations

of carbon elementary carbon in three modifications, based on the bond structures sp3 and: Diamond, graphite and Fulleren. Apart from these three modificationsthere are further different forms of elementary carbon.

modifications

diamond

see also: Diamond
The sp3 - kovalent tetragonally bound carbon atoms do not possess free electrons. The material is an insulator with a gap of 5.45 eV, thatvisible light does not absorb.Addition of foreign atoms produces conditions in the gap and changes thus the electrical and optical characteristics. Thus the yellowish clay/tone many is to be due natural diamonds to nitrogen, during with boron endowed diamond bluish looks semiconducting andare. The diamond is converted under luftabschluss at high temperatures into graphite. It burns already with approx. 700-800°C to carbon dioxide.

Generally diamond applies under normally conditions (1 bar, 25°C) as the metastable form of carbon. Due to newer research is this however no longer surely, because
1) thermodynamic stability on low P-T-conditions only extrapolates is,
2) with equilibrium investigations the influence of the environment - slight traces of impurities, which lie below the today's detection border, know already drastic effects on the equilibrium positiona reaction having one did not consider/becomes (s.h.Carpenter, M.A: Thermodynamics OF phase of transit ion in mineral: A macroscopic approach, in: Stability OF of mineral, Chapman & resound to London, 1992 or Salje, E.: Phase of transit ion in ferrous reading TIC and coelastic Crystals, Cambridge UniversityPress, Cambridge 1990)) and finally
3) Experiments of Chinese scientists show that in a hydrothermalen reaction between metallic sodium and magnesium carbonate carbon and diamond co-exist stably next to each other.

graphite

see also: Graphite
The sp2 - kovalent hexagonally bound carbon atomsform high-strength levels. The levels among themselves are only loosely bound over Van that Waals forces. Macroscopically the fissileness dominates along the planar levels. Since the levels are so thin, their extraordinary firmness does not go with graphite into action.

Because of this structure graphite behavesvery anisotropic: Along the crystal planes is thermal and electrically very conductive graphite, the line of warmth or charges from crystal plane to crystal plane is against it relatively badly.

Fullerene

see also: Fulleren
a hexagonal structure is planar. Replacedone some hexagons by pentagons, develops a spatial structure, the Fullerene. The sp2 - Connections do not lie any longer in one level, but form a spatially closed thing. The smallest possible structure requires 60 Carbon atoms and resembles a football in the structure. The molecule balls among themselves commit themselves over a weak Van that Waals -, exactly the same as with the graphite the basal levels to reciprocal effect. From 60 and/or. 70 atoms existing forms can be isolated and crystallized and be able therefore as modification (EN) to apply.

further ones Forms of carbon

graph

as graphs one designates an monoatomic layer of carbon, which corresponds to one basal level. As is the case for alkenes the ending refers EN to insatiated double bonds in the carbon rings (stress: graph én). One tries, mono situations in more macroscopicTo manufacture expansion, in order to use the high anisotropy of the electrical characteristics along and perpendicularly to the level for the production of new semiconductors. Strictly taken one cannot call graphs modification, since it concerns practically a two-dimensional crystal.

carbon nano-tubes

see also: Carbon nano-tube
A further form of carbon are cylindrically arranged, sp2 - bound carbon atoms. Their geometry develops from a planar layer graphite, which is rolled up to a cylinder. The developed tube can be additionally still rotated, howthe electrical characteristics change. Several einwandige tubes can lie concentrically into one another, so that one speaks of multi-whale LED carbon nanotubes (MWCNT), contrary to single whale LED carbon of nanotubes (SWCNT).

carbon nano-foam

carbon nano-foam is a coincidentally oriented, netlike arrangementof carbon Clustern, similarly of glass carbon, only with clearly larger cavities. Their average diameter is with six to nine nanometers. Carbon nano-foam an aero gel with a density of 0.2-1.0   gram is technically spoken ⁄ cubic centimeters. Still lower become partialDensities with ungwöhnlichen magnetic characteristics described (see discussion: Carbon).

carbon fibers

see also: Of

graphite-like sp2 consists carbon fiber carbon fibers - bound carbon. In an ideal fiber the graphite situations are present arranged as oriented in a long web, the graphite levels alongthe Faserachse. In reality the levels are disturbed strong and train only local one orders. The measure of the disturbance affects the firmness.

Carbon fibers are zugfest and therefore in composite materials are used very much.

soot

see also: Soot
sootconsists likewise of carbon on graphite basis. The more purely the soot, the characteristics of graphite step out the more clearly. Lamp or candle soot is strongly contaminated with organic compounds, which prevent the education of larger graphite federations.

to activated charcoal

see also activated charcoal
Careful Graphitieren of organic materials, like for example coconut bowls, leads to a porous carbon. The cavities stand as with one another with a sponge in connection and form a very large internal surface. Activated charcoal filters solids from liquids and can gases adsorb.

to glass carbon

see also glass carbon.

Glass carbon is a high-technological material from pure carbon, which unites glasslike and ceramic characteristics with those of the graphite. Contrary to graphite glass carbon possesses a filler-like microstructure. Thus a large resultsVariety of positive material properties.

tubular ones aggregated diamond nano-tubes

a special form diamonds are ADNRs, tubular aggregated diamond nano-tubes.

amorphous carbon

in amorphous carbon (AC) the atoms without langreichweitige order are interlaced. The material leaves itself alsoalmost arbitrary FR ²: FR ³ hybridizing conditions synthesize, whereby the material properties turn into flowing from those of the graphite to those of the diamond. With a FR ³ hybridizing portion >of %   70 one speaks of tetrahedrally amorphous carbon (TAC). This material draws by highelectrical resistance, extreme hardness and optical transparency out. The synthesis can take place by means of PVD - methods.

carbon compounds

of examples of some inorganic chemical compounds, which contain carbon:

• Oxides of carbon: Carbon mono oxide (CO), carbon dioxide (CO ₂), as well as its Suboxide:Tri carbon dioxide (C ₃ O ₂), Tetrakohlenstoffdioxid (C ₄ O ₂) and Pentakohlenstoffdioxid (C ₅ O ₂)
• carbonic acid (H ₂ CO ₃) as well as their salts, the carbonates.
• Kohlenstoffdisulfid (carbon disulfide, CS ₂).
• Alloy from ironand carbon, steel.
• Carbon nitrogen compound

entire living nature is based on organic carbon compounds so mentioned, mainly in connection with hydrogen, oxygen and nitrogen. Between the earth, its oceans and the terrestrial atmosphere a continuous river of carbon takes place. ThisOne calls process carbon cycle.

Organic chemistry enclosure, due to the ability of carbon, long chains and kovalente connections with other atoms to form, more connections than entire inorganic chemistry. Also biochemistry is a part of organic carbon chemistry.

raw materials for the carbon production

the Inkohlung increases the carbon content of organic substances within geological periods. This process led to the emergence of brown and hard coal from plant material of the carbon. A faster procedure is heating under inert gas.The Karbonisierung (to approx. 1900°C) and Graphitierung and/or. Graphitisierung (above 2000°C) lead to high carbon enrichments, depending upon quantity in minutes or few days.

Carbon content in Gew. - % of some raw materials for the carbon production:

• Anthracite coal: >90%
• charcoal: 90%
• hard coal: 85-90%
  • Coke (by Karbonisierung of hard coal): 98%
• brown coal: 60-75%
• oil: 85-90%
• natural gas: 85-95%
• peat: 56%
• wood: 45-50%
  • charcoal (by Karbonisierung of wood): 80-90%

Web on the left of

Wiktionary: Carbon - word origin, synonyms and translations

Commons: Carbon- Pictures, videos and/or audio files

• Growth Mechanism and Structure OF carbon Nanotubes (in English)
• to carbon on Chemieseite.de

see also: organic chemistry, radio carbon method, polymer, carbon-lowers, carbon dioxide