Organic chemistry

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Organic chemistry

• The carbon compounds

Prof. Paola Valentinis 2A- 2B
Scholastic year 2006/07
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Glossary
Coal Organic Combustion Rocks plants Sweeteners Laboratory Soaps Term Chemist Theory Mysterious Fibres Phenomena inorganic
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Organic chemistry
Fill in the blanks using the new words
Organic chemistry was the term applied originally
to the study of substances connected directly
with animals and plants, so it is derived from
the word organism. For this reason it received
the name organic. Such substances were thought to
contain a mysterius vital force wich made it
impossible for man to prepare them from inorganic
ingredients. But in 1828 the German chemist
Friedrich Wohler attempted to prepare crystals of
the inorganic salt ammonyum cyanate by
evaporating its solution . Istead, he obtained
crystals of urea an organic subtance already
known for 50 years an the main constituent of
urine. Over the following years further organic
substances were prepared in the laboratory and
eventually the vital force theory was
abandoned. Today the study of organic chemistry
is very important because it help us to
understand the phenomena living in the world.
Synthetic fibres, plastic, medicines, artificial
sweeteners are product of industrial organic
chemistry and the energy that man uses in every
industrial activity derives mainly from the
combustion of organic material found in coal an
crude oil.
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carbon

• The special role of carbon in the chemistry of
  the elements is the result of a combination of
  factors, including the number of valence
  electrons on a neutral carbon atom, the
  electronegativity of carbon, and the atomic
  radius of carbon atoms (see the table below).
• The Physical Properties of Carbon
• Electronic configuration 1s2 2s2 2p2
  Electronegativity 2.55 Covalent radius 0.077 nm
• Carbon has four valence electrons 2s2 2p2 and
  it must either gain four electrons or lose four
  electrons to reach a rare-gas configuration. The
  electronegativity of carbon is too small for
  carbon to gain electrons from most elements to
  form C4- ions, and too large for carbon to lose
  electrons to form C4 ions. Carbon therefore
  forms covalent bonds with a large number of other
  elements, including the hydrogen, nitrogen,
  oxygen, phosphorus, and sulfur found in living
  systems.
• Because they are relatively small, carbon atoms
  can come close enough together to form strong CC
  double bonds or even C C triple bonds. Carbon
  also forms strong double and triple bonds to
  nitrogen and oxygen. It can even form double
  bonds to elements such as phosphorus or sulfur
  that do not form double bonds to themselves

Even though organic chemistry focuses on
compounds that contain carbon and hydrogen, more
than 95 of the compounds that have isolated from
natural sources or synthesized in the laboratory
are organic.
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Carbon and life

• Several factors make carbon essential to
  life.
• The ease with which carbon atoms form bonds to
  other carbon atoms.
• The strength of C-C single bonds and the covalent
  bonds carbon forms to other non metals, such as
  N, O, P, and S.
• The ability of carbon to form multiple bonds to
  other non metals, including C, N, O, P, and S
  atoms.
• These factors provide an almost infinite variety
  of potential structures for organic compounds,
  such as vitamin C shown in the figure below.

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hydrocarbons

• Compounds that contain only carbon and hydrogen
  are known as hydrocarbons

• Those that contain as many hydrogen atoms as
  possible are said to be saturated. The saturated
  hydrocarbons are also known as alkanes.

• Carbon not only forms the strong C C single bonds
  found in alkanes, it also forms strong CC double
  bonds. Compounds that contain CC double bonds
  were once known as olefins (literally, "to make
  an oil") because they were hard to crystallize.
  (They tend to remain oily liquids when cooled.)
  These compounds are now called alkenes.
• Alkenes are examples of unsaturated hydrocarbons
  because they have fewer hydrogen atoms than the
  corresponding alkanes

Compounds that contain C C triple bonds are
called alkynes. These compounds have four less
hydrogen atoms than the parent alkanes
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Structure and Nomenclature of Hydrocarbons
The alkanes in the table above are all
straight-chain hydrocarbons, in which the carbon
atoms form a chain that runs from one end of the
molecule to the other. The generic formula for
these compounds can be understood by assuming
that they contain chains of CH2 groups with an
additional hydrogen atom capping either end of
the chain. Thus, for every n carbon atoms there
must be 2n 2 hydrogen atoms CnH2n2.
Because an alkene can be thought of as a
derivative of an alkane from which an H2 molecule
has been removed, the generic formula for an
alkene with one CC double bond is CnH2n.
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pollution

• Hydrocarbons are a
  precursor to ground-level ozone, a
  serious air pollutant in cities across the United
  States. A key component of smog, ground-level
  ozone is formed by reactions involving
  hydrocarbons and nitrogen oxides in the presence
  of sunlight. Hydrocarbon emissions result from
  incomplete fuel combustion and from fuel
  evaporation. Today's cars are equipped with
  emission controls designed to reduce both exhaust
  and evaporative hydrocarbons.

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Try yourself synthetizes you an organic
mixtureMAKING SOAP FROM OLIVE OIL

• INGREDIENTS125 cm3 of vegetable oil100 cm3 of
  water20 g of caustic soda (sodium
  hydroxide)salt (if required)essential oil or
  perfume (optional)

APPARATUSsafety gogglesbeakerglass rodmould
for setting soap

• METHOD
• Weigh out your caustic soda onto a folded piece
  of paper. DO NOT TOUCH IT.
• Pour the oil and water into a big beaker and stir
  with a glass rod until you make an emulsion.
• Carefully add the caustic soda, slowly and
  stirring all the time. DON'T TOUCH IT !
• Keep stirring until a thick paste forms. This
  could take half an hour.
• If you still don't have a paste after half an
  hour, stir in 4 spatulas of salt.
• Add essential oil or perfume if you want.
• Pour into mould and leave to set for a few days.
• Keep your fingers crossed !

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Lab- work

• Write a purpose for the lab in you notebook.
  You might also wish to think about the following
  questions. They will help you prepare for the
  lab, but you need not turn them in at the
  beginning of class.

• What reaction is described by the word
  saponification. What are the products from this
  reaction and what are the required reactants?

• Draw out the full structure for three of the
  carboxylic acids listed in books table. Identify
  all of the polar bonds, and find the polar and
  non-polar regions of the molecule.

• What is the most dangerous part of the lab?

• Why is it critical to clean up all spills
  immediately?

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bibliography
GCSE chemistry Complete Revision Practice
Roggi- Picking BIO-CHEM Zanichelli
www. thinkQuest.org
www.chemed.chem.purdue.edu.html
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Thanks for your attentions