Transcript Document

What you should remember from last lecture
1. Organic compounds are based on carbon, and
form the basis of biology and of many of the
materials that you experience every day.
2. Carbon atoms make 4 covalent bonds, to other
carbons and to many other elements in the
periodic table.
3. Carbons with 4 single bonds are tetrahedral.
4. Organic molecules are really 3-dimensional blobs,
not flat (like most drawings).
What you should remember from last lecture
1. Alkanes are simple CnH2n+2 (saturated)
hydrocarbons. Cycloalkanes are ring structures
with molecular formulae CnH2n.
2. Several isomers (different structures) are possible
for most molecular formulae.
3. For practice, can you draw four different
hydrocarbons with the molecular formula C6H14?
How about four different C5H10 hydrocarbons?
4. Shorthand drawing methods are often used when
drawing organic compounds. Remember, carbon
makes 4 bonds, whether all 4 are shown or not.
What you should remember from last lecture
1. Alkenes are compounds with C=C double bonds,
and alkynes are compounds with C-C triple bonds.
2. Petroleum (oil) is the source of a wide array of
solvents, fuels, and compounds from which many
products can be made.
3. Petroleum refining begins with distillation, which
separates the hydrocarbons according to their
boiling points.
4. Cracking is a process that breaks larger molecules
into smaller, more valuable ones.
What you should remember from last lecture
1. Alkanes, Alkenes, and Alkynes.
2. Structural Diversit.y
3. Petroleum (oil) is the source of a wide array of
solvents, fuels, and compounds from which many
products can be made.
4. Distillation, Cracking, and Reforming are key steps
in petroleum refining.
5. Coal is a complex mixture of large molecules that
cannot easily be separated into pure compounds, yet
represents the major fraction of fossil fuel reserves.
What you should remember from last lecture
• Organic compounds are ensembles of functional
groups: commonly occurring groups of atoms with a
characteristic reactivity.
• Halogens (fluorine, chlorine, bromine, iodine) are
simple functional groups. Chlorinated hydrocarbons
are highly useful, but some have harmful properties.
• Polymers are extremely large molecules, assembled
from smaller molecules called monomers.
What you should remember from last lecture
• Molecular weight, degree of branching, and amount
of crosslinking can affect the properties of a
resulting polymer.
• Stereoisomers: Compounds that differ in the 3-D
placement of atoms in space. Cis vs. trans C=C
bonds can affect the properties of a molecule.
• Polymerization (bond formation between
monomers) can be through addition (polyethylene,
polystyrene, PVC, others) or condensation
(polyamides, polyesters).
What you should remember from last lecture
Many common polymers are condensation polymers.
These include polyesters and polyamides.
A plasticizer is often added to a polymer to make it soft
and plastic.
Highly crosslinked polymers (like epoxy) tend to be
hard, non-flexible, and durable.
Composite materials are composed of a reinforcing
material (glass fibers, graphite fibers, others) embedded
in a polymer matrix (epoxy, polycarbonate, others).
What you should remember from the last lecture
• Water is a polar molecule, and hydrocarbons are nonpolar. Water will interact strongly with other polar
molecules, but not with non-polar (greasy) ones.
• Fats and Oils are tri-esters of glycerol and 3 fatty
acids. These tri-esters can be converted back to the
component fatty acids and glycerol, using NaOH (lye).
• In water, fatty acids form micelles, in which the nonpolar tails cluster together and the polar acid groups
point out toward the water.
What you should remember from the last lecture
Fats (triglycerides) can be completely (or partially)
converted (saponified) into fatty acids and glycerol,
or fatty acids and mono- (or di-) glycerides.
Fatty acids are the basis of soaps. These are
effective cleaning agents, as they form micelles with
non-polar interiors. Fatty acid salts with calcium
are insoluble, and form soap scum.
Alkyl benzene sulfonates, alkyl sulfates and nonionic sufactants (PEG) are cleaning agents that
remain soluble when complexed with calcium.
What you should remember from the last lecture
Some organic molecules are Chiral. Chiral
objects are not identical to their mirror images.
Molecules that contain a carbon that is bound to
4 different things are usually chiral.
Many important biomolecules (molecules of life)
are chiral, including most carbohydrates and
amino acids, the building blocks of proteins.
Carbohydrates (saccharides) are sugars. Simple
sugars have the molecular formula Cn(H2O)n.
These compounds usually exist as 5- or 6membered rings containing one oxygen atom.