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Up to this point the matter that we have
discussed has been inorganic matter.
Scientist tend to study either the organic
or inorganic matter.
For example in chemistry, organic chemistry
is taught a separate course and organic chemist is a subdiscipline in
Living matter is organic but not all
non-living matter is inorganic so that division is a generalization.
The division based on whether the compound
or matter contains carbon is a more accurate one.
The first two points are related since
substances with low melting point will exist as a liquid.
Inflammable and flammable are synonyms.
The low solubility in water is expected
since organic compounds are generally non-polar.
This is similar to silicon which also is a
column four element.
The field of organic chemistry is filled
with nomenclature for classifying compounds.
The carbon atoms in organic molecules are
either in a chain or in a ring.
Benzene as we will see later has a
These concepts or terms will become more
clear as we describe the molecules.
These are all flammable gases. Butane is the
gas the the cylinders that I use for the demonstrations. Propane is the gas
that is used in BBQ and portable heaters.
The alkanes have the formula CnHn+2
Demo of ball and stick model to show 3D
arrangement of atoms.
Eclipsed vs. staggered orientation for
Stable conformation for propane
Octane rating of a gasoline is an indication
of the resistance to premature detonation. The higher the octane number the
less likely that premature detonation or knocking will occur. The term octane
number was used because isooctane an isomer of octane was used as the
reference for an octane number of 100.
We will define what an isomer is in the next
Octane ratings for gas is typically 87, 89
Show ball and stick model to explain why
there are no isomers.
To describe the isomer one may write the
formula to indicate the manner in which the atoms are arranged in the
Put together an isobutane model from methane
and propane models.
This is the structure of isooctane which is
an isomer of octane.
We can build up different molecules by
attaching different radicals.
We will consider replacing the hydrogen
atoms with other atoms or radicals.
So far we have described saturated
Saturated fats are fats that have as many
hydrogen as it may have.
Alkenes are therefore unsaturated
Formula for alkenes is CnH2n.
Ethylene - 14 million tons produced annually
- used to make polyethylene
Propylene - 7 million tons produced annually
- used to make polypropylene
Note that every carbon has four bonds and
every hydrogen has one bond.
Mdel of ethylene and bonding.
Acetylene is a gas that is used in welding
and is extremely flammable.
Ethyl alcohol is the alcohol in alcoholic
Methyl alcohol is highly toxic, however
ethyl alcohol is also toxic. In a large enough dose ethyl alcohol is
Ball and stick model of alcohols
These compounds are considered aliphatic
even though they are in a ring because they are similar to the open chain
molecule except that they are placed in a ring.
Use methane or propane model to show how
cyclopropane is made.
Resolving the structure of benzeneis an
Several pieces of information was known
The chemical formula was known.
The effect of replacing the hydrogen atoms with different atoms was
This is a fairly accurate picture of
benzene. It is a 2D molecule.
Difference between conformation isomers and