CARBON AND ITS COMPOUNDS

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CARBON AND ITS COMPOUNDS

• CARBON IS A NON-METAL
• SYMBOL C
• ATOMIC No 6
• VALENCY 4
• Group No 14
• It occurs in elemental form
  as well as in combined form such as
• CARBONATES, COAL, PETROLEUM AND CO2
• The compounds of carbon are called
  ORGANIC COMPOUNDS.

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• Carbon is one of the least abundant elements in
  the Earth's crust, but the fourth most abundant
  element in the universe by mass after hydrogen,
  helium, and oxygen.
• It is present in all known lifeforms, and in the
  human body carbon is the second most abundant
  element by mass (about 18.5) after oxygen
• This abundance, together with the unique
  diversity of organic compounds and their unusual
  polymer-forming ability at the temperatures
  commonly encountered on Earth, make this element
  the chemical basis of all known life.

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Allotropy Allotropes

• Allotropes are different physical forms of the
  same element which have same chemical properties
  but different physical properties, and the
  phenomenon is known as Allotropy.
• Carbon exhibit allotropy.
• The three relatively well-known allotropes of
  carbon are amorphous carbon, (charcoal, lampblack
  (soot) and activated carbon ) graphite, and
  diamond.

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Allotropes of carbon

• There are several allotropes of carbon of which
  the best known are graphite, diamond, and
  amorphous carbon.
• The physical properties of carbon vary widely
  with the allotropic form. For example, diamond is
  highly transparent, while graphite is opaque and
  black.
• Diamond is among the hardest materials known,
  while graphite is soft enough to form a streak on
  paper (hence its name, from the Greek word "to
  write").
• Diamond has a very low electrical conductivity,
  while graphite is a very good conductor.
• Under normal conditions, diamond has the highest
  thermal conductivity of all known materials.
• All the allotropic forms are solids under normal
  conditions but graphite is the most
  thermodynamically stable.

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Appearance

Clear (diamond), black (graphite)
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Graphite ore Raw diamond crystal
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Structure of Diamond and Graphite
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Allotropes of Carbon - Fullerenes

• In 1985 the carbon structure family was completed
  by a new modification of pure carbon. With the
  discovery of the fullerenes by Curl, Smalley and
  Kroto 1 and additionally with the possibility
  for the production of fullerenes in large amounts
  shown by Krätschmer and Huffman 2 in 1990 the
  scientific competition in experimental and
  theoretical research was started.

structure of a buckyball
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BONDING IN CARBON COMPOUNDS THE COVELENT
BOND
A bond formed between two atoms by mutual
sharing of electrons between them so as to
complete their octet is known as covalent bond.
A carbon atom has 4 electrons in its valence
shell, so it needs 4 electrons to attain stable
electronic configuration of nearest noble gas.So
carbon forms bond by sharing its valence electron
with any other atom.

C
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Formation of methane molecule
H
C
4
C
H
H
H
--?
H
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Structure of Methane CH4
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Tetravalent Nature

• Due to its tetravalent nature carbon always form
  covalent bonds by sharing electrons with one,
  two, three or four carbon atoms or atoms of other
  elements or groups of atoms as discussed earlier.
  The tetra covalency of carbon atom allows it to
  combine easily with other carbon atoms to form a
  stable chain like structure i.e., exhibiting the
  property of catenation. Catenation usually occurs
  because the atom-to-atom covalent bond is quite
  strong. The chains having different chain lengths
  and structures and combines with different
  elements it leads to the formation of a large
  number of compounds

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Unique properties of Carbon atom

• Carbon has the ability to form very long chains
  of interconnecting C-C bonds. This property is
  called catenation.
• Carbon-carbon bonds are strong, and stable. This
  property allows carbon to form an almost infinite
  number of compounds in fact, there are more
  known carbon-containing compounds than all the
  compounds of the other chemical elements combined
  except those of hydrogen (because almost all
  organic compounds contain hydrogen too).
• The simplest form of an organic molecule is the
  hydrocarbona large family of organic molecules
  that are composed of hydrogen atoms bonded to a
  chain of carbon atoms.

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Formation of covalent bond in carbon compounds

• Formation of Strong C-C Covalent Bonds
• The single bond formed between the carbon atoms
  is strong. This results in the formation of
  stable compounds. Carbon atom can also form
  stable bonds with other atoms like H, Cl, Br, O,
  etc.
• Formation of C-C Multiple Bonds
• Due to its small size the carbon atom can also
  form multiple bonds i.e., double and triple bonds
  with not only carbon but with atoms of other
  elements like oxygen, nitrogen, etc. The
  formation of these multiple bonds gives rise to a
  variety in the carbon compounds.

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Formation of C-C Multiple Bonds
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Types and number of bonds Structure
Linked to four atoms with four single bonds. Tetrahedral geometry (sp3 hybridisation)
Linked to three atoms with two single and one double bond. Trigonal geometry (sp2 hybridisation)
Linked to two atoms with one single and one triple bond. Linear geometry (sp hybridisation)
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Homologous series

• All organic compounds are made up of a
  progressively building chain of carbon atoms with
  a number of compounds having the same functional
  groups.
• Such a series of similarly constituted compounds
  are called a homologous series.
• Members of a homologous group are similar in
  structure and display similar chemical
  characteristics.
• The two consecutive members of the series differ
  in their molecular formula by a 'CH2' group.

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Some important characteristics of the homologous
series

• All the members conform to a general molecular
  formula and have a similar functional group.
• Each consecutive member differs in the molecular
  formula by a unit of 'CH2'.
• All the members of the series exhibit similar
  properties, but the extent of the reactions vary
  with increasing relative molecular mass.
• The physical properties, such as solubility,
  melting point, boiling point, specific gravity
  etc. show a gradual change with the increase in
  their relative molecular masses

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Homologous series of Alkanes
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IUPAC Names

• With the large growth of carbon compounds, it was
  necessary to name these compounds in a more
  systematic way. A committee called the
  'International Union for Pure and Applied
  Chemistry' (IUPAC) put forward a system of giving
  proper scientific names to carbon based
  compounds. The names derived by their rules are
  the names followed all over the world and in
  short are called IUPAC names.
• In this system the name of a carbon compound has
  three main parts as mentioned below
• Wood Root
• This denotes the number of carbon atoms present
  in a given molecule. For e.g., C1-Meth, C2- Eth,
  C3 - Prop, C4- But.
• Suffix
• The suffix denotes the type of bonds or the
  functional group present in the carbon chain,
  e.g.
• Type of bondFunctional group'ane' (single
  bond)'ol' for alcohols (-OH)'ene' (double
  bond)'al' for aldehydes (-CHO)'yne' (triple
  bond)'oic acid' for carboxylic acid (-COOH)

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IUPAC Names
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Nomenclature of compounds having polyfunctional
groups

• When an organic compound contains two or more
  functional groups, one group is called the
  principal functional group while the others are
  called the secondary functional groups and are
  treated as substituents The order of preference
  for principal group is Carboxylic acid gt acid
  anhydrides gt esters gt acid halides gt amides gt
  nitrites gt aldehydes gt ketone gt alcohols gt amines
  gt double bond gt triple bond
• When the functional groups act as substituents,
  they ar named as
• Functional groupPrefixFunctional groupPrefix-
  COOHCarboxy-CHOFormyl-COORAlkoxy cabonyl or
  CarbalkoxygtCOOxo or Kelo-COCLChloroformyl-OHHydrox
  y-CONH2 Carbamoyl-SHMecaplo-CNCyano-NH2
  Amino-ORAkoxyNHImino

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• For e.g., the following compound can be named as
• Word root But (C4)
• Prefix 3, chloro
• Suffix -ol
• Name 3-chloro butanol

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Trivial Names, IUPAC Names and Molecular Formula
of some Organic Compound
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ABOUT CARBON

• Carbon is the sixth most abundant element in the
  cosmos, yet its abundance in the earth's crust
  does not even make it among the top ten elements
  on our planet. There are more known chemical
  compounds of carbon than any other element except
  for oxygen and hydrogen. Carbon composes
  compounds with diverse properties such as
  graphite and diamond, as well as the recently
  discovered Buck Minster Fullerenes, or
  buckyballs. Carbon plays a critical role on Earth
  as the "stuff" that Life is made from. Every
  living cell, plant or animal contains carbon.
  Even in its pure, elemental form carbon is very
  versatile. 

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Carbon Herethereand everywhere

• Graphite is found in large deposits in Sri Lanka,
  Malagasy Republic, the former USSR, South Korea,
  Mexico, and Czechoslovakia. Economic deposits at
  Val Chisone (Italy). Small hexagonal crystals in
  marble at Ogdensburg, New Jersey (USA) and in
  gneiss at Edison, New Jersey (USA). 
• Natural It is formed in high-grade metamorphic
  rocks as a final product of the carbonisation of
  organic materials. It is probably also a primary
  magmatic substance in some pegmatite's and
  hydrothermal veins. 
• Synthetic Coke is a graphite product that is
  about 94 carbon. It is produced by heating soft
  coal in an oven that has no access to air. Most
  of the impurities sublime off, leaving fairly
  pure carbon.

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Carbon Herethereand everywhere

• Graphite is found in large deposits in Sri Lanka,
  Malagasy Republic, the former USSR, South Korea,
  Mexico, and Czechoslovakia. Economic deposits at
  Val Chisone (Italy). Small hexagonal crystals in
  marble at Ogdensburg, New Jersey (USA) and in
  gneiss at Edison, New Jersey (USA). 
• Natural It is formed in high-grade metamorphic
  rocks as a final product of the carbonisation of
  organic materials. It is probably also a primary
  magmatic substance in some pegmatite's and
  hydrothermal veins. 
• Synthetic Coke is a graphite product that is
  about 94 carbon. It is produced by heating soft
  coal in an oven that has no access to air. Most
  of the impurities sublime off, leaving fairly
  pure carbon.

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• Diamond Splendid crystals of Diamond occur in
  the kimberlites of South Africa, Yakutia (former
  USSR), Murfreesboro, Arkansas (USA), Brazil,
  Zaire, Sierra Leone and Ghana. Small,
  nongem-quality crystals are found in Brazil,
  Venezuela, Zaire and other countries. 
• Natural It is formed in ultramafic rocks,
  especially kimberlite breccias, and in detrital
  sedimentary deposits derived from them, in river
  and marine placers. A rare form of hexagonal
  "diamond" known as Lonsdaleite is found in
  certain meteorites, such as those from Canyon
  Diablo, (USA). 
• Synthetic Most industrial-grade diamonds are
  produced, with the aid of catalysts, by
  subjecting high-grade graphite to extremely high
  temperature and mechanical pressure over a period
  of several days or weeks. Dr. Guy Suits of the
  General Electric Company synthesized the first
  man-made diamonds in 1957. 

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Third and the most recently discovered
allotrope of Carbon....
FULLERENES
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INTRODUCTION

• In 1985 the carbon structure family was completed
  by a new modification of pure carbon. With the
  discovery of the fullerenes by Curl, Smalley and
  Kroto 1 and additionally with the possibility
  for the production of fullerenes in large amounts
  shown by Krätschmer and Huffman 2 in 1990 the
  scientific competition in experimental and
  theoretical research was started.

structure of a buckyball
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• Fullerenes are polyeders build up by n three
  times coordinated carbon atoms with 12 pentagons
  and (n) hexagons, were the minimum for n equal 20
  is. Fullerenes fulfil the EULER's theorem, were a
  polyeder build up from pentagons and hexagons has
  to contain exact 12 pentagons, to build a closed
  structure. Following this rule, the dodekaeder
  with 20 carbon atoms is the smallest possible
  fullerene. Actual the smallest fullerene is the
  C60, because important for the stability of the
  structure is, that no pentagons are side by side.
  This is described by the Isolated Pentagon Rule
  (IPR). If two pentagons are annulled, the tension
  of the binding is increasing and the structure is
  not anymore energetic stable.

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CHEMICAL AND PHYSICAL PROPERSTIES

• The carbon atoms in fullerenes are spm (m2...3).
  The free valence electrons on the cage building a
  strong localized p-electron system. This
  p-electron system influences chemical reactions
  of the fullerenes. In chemical reactions
  fullerenes are not reacting aromatic ("super
  benzene"), they show aliphatic behaviour.
• Good solvents for fullerenes are CS2,
  o-dichlorobenzene, toluene and xylene 7, 8, 9.
  Fullerenes are insoluble in water and stabile at
  air. Thin layers of fullerenes are coloured from
  yellow to yellow-green.

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• Because of pp-electron transitions solutions of
  fullerenes are coloured 10
• - C60 purple/violet red - C70 brick-red - C76
  light yellow-green - C2v-C78 maroon, D3-C78
  golden, - C84 brown and - C86 olive-green.
• By heating fullerenes without air up to 1500 C
  they transform to graphite. These fullerenes
  were discovered in 1985 and after solid phase
  research they have been found in geological
  material and in the flames of candles.

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SPECIES OF FULLERENES

• Following species of fullerenes are known -
  fullerenes - fullerites 11 - fullerides 11
  - endohedral fullerenes - exohedral fullerenes
  - heterofullerenes 12, 13 - metcars.
• Professors Curl and Smalley of the United States
  and Professor Sir Kroto from the United Kingdom
  were awarded the Nobel Prize in chemistry in 1996
  for the discovery of the buckyball.

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Fullerenes C-140, C-260, C-960
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NANOTUBES

• The discovery in 1985 of buckminsterfullerene
  opened a new era for the chemistry of carbon and
  for novel materials. The Japanese Sumi Ijima
  discovered Nanotubes in 1991. The Nanotubes
  synthesised in the laboratory showed remarkable
  mechanic properties as well as thermal
  conductivity and resistance to flame. These
  Nanotubes consist of layers of graphite in the
  form of cylinders and often closed at both ends.
  They can exist as single and multi walled
  Nanotubes. Normally their diameter is only a few
  nanometres and their length a millimetre

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• Nanotubes can be obtained by mixing the soot of
  Nanotubes of carbon in water and surfactant. This
  viscous solution is rotated in a substance
  capable of aggregating the Nanotubes. A liquid is
  then injected to aid the formation of a
  rectangular section, which rolls itself into a
  cylinder and thus forms carbon Nanotubes. 
  Another method is to decompose methane with a
  catalyst. The enlargement of the basal plans of
  graphite on existing surfaces causes Nanotubes
  without extremities to extend and lepaissement
  the tubes. These tubes are semi-conductors or
  metallic conductors depending on small variations
  of their angle of curvature or diameter. This
  angle defines the type of Nanotubes (armchair,
  zig zag or chiral) and it is determined by the
  way the layers of graphite wrap around and
  interact with themselves. Their properties of
  conduction depend on their diameter and the way
  they are helicoidal. Nanotubes are tested with
  scanning tunnelling microscopy at low
  temperatures, and a measure of their electronic
  and physical structure. Even with Nanotubes made
  by different methods, the results are
  complimentary and confirm that the conduction is
  only in one dimension.

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• Furthermore, fullerenes are very important in
  pharmaceutical applications. Wudl synthesised a
  derivative of a fullerene which is soluble in
  water. It seems to inhibit the activity of HIV
  and could be used in a medicine for the treatment
  of AIDS. Nanotechnology is thus a domain of
  central importance, at the forefront of
  chemistry, physics, engineering and materials
  science. Nanotechnology find ways of manipulating
  atoms and molecules in an effort to construct new
  materials and different molecular stratagems.
• In conclusion, carbon is truly important for
  chemistry and for life. It is essential that we
  continue to study the chemistry of carbon to
  increase understanding of ourselves and our
  environment and to improve the quality of life.