Organic Chemistry
A Brief Introduction
Text reference: Ch 20
• What isn’t it?
• Organically grown fruits & veggies
• It IS a branch of chemistry that deals with
molecules containing the element carbon,
bound to other elements.
• Many (most) of these molecules are produced
by living things (organisms  organic)
• So why do we call them “organically grown”?
• What carbon-containing molecules can you think
of (maybe from biology???)
• Glucose C6H12O6
organic
• Sucrose, dextrose and all the other “oses”
• Sugars are organic
• CO2 – carbon dioxide – inorganic
• CO – carbon monoxide – inorganic
• Most other carbon-containing molecules are
organic
• Many can be duplicated in laboratory
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Any ideas?
See p. 699
Fuel (from decayed living matter)
Plastics
PVC
Velcro
Artificial sweeteners
• How many valence electrons does carbon
have?
• 4
• Carbon bonds readily with many, many, many
other elements in a billion different ways.
• It’s very versatile.
• (BTW: Sulfur does the same thing in the nonliving world… but that’s the stuff of earth
science)
• The simplest of organic molecules.
• What elements do you suppose hydrocarbons
contain?
• Hydrogen & carbon
• Simplest of simplest = methane
• Methane = one carbon atom, surrounded by 4
hydrogens, each sharing valence electrons
• Organic molecules are bonded covalently
• Lewis dot structures show shared electrons as
dashes, instead of two dots.
• What is the chemical formula for methane?
• CH4
• Each carbon molecule has ____ bonding
possibilities
• 4
• In hydrocarbons, carbon bonds with itself and
hydrogen
• If the hydrocarbon is “saturated”, then all four
available bonds of carbon are shared, or filled,
by other atoms.
• Saturated hydrocarbons are called alkanes
• When naming, alkanes all end in “ane”
• One carbon = methane
• Two carbons = ethane
• Ethane is a molecule made up of two carbons,
surrounded by hydrogen using all the other
available bonding spaces
• What is the formula for ethane?
• CH3CH3
# of
carbons
Name
formula
Structure diagram
1
Methane CH4
Draw these all in your
2
Ethane
CH3CH3
notes, below your table
3
Propane
CH3CH2CH3
Label them
4
Butane
CH3CH2CH2CH3
5
Pentane
CH3CH2CH2CH2CH3
6
Hexane
CH3CH2CH2CH2CH2CH3
7
Heptane
CH3CH2CH2CH2CH2CH2CH3
8
Octane
CH3CH2CH2CH2CH2CH2CH2H3
9
Nonane
CH3CH2CH2CH2CH2CH2CH2CH2CH3
10
decane
CH3CH2CH2CH2CH2CH2CH2CH2CH2CH3
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(QUIZ TOMORROW ON PREFIXES and formulas)
meth 1, starts with m, like mono does
eth 2, follows meth, but isn’t mono, so drop the m
prop- 3, How can you remember this?
But- 4, rhymes with cute, which has four letters
The rest of the prefixes are the same as the ones
you’ve already learned for covalent naming
• penta, 5, as in pentagon
• hex – hex has an “x” like six does
• hept - seven
• oct – octopus has 8 legs
• non- – sounds like nine
• dec- – a decade has ten years
• see board for this
• To name these, add the prefix “cyclo” in front
of the alkane name
• ex: hexane becomes cyclohexane
• When the attached groups are made up of
hydrocarbons, these are called alkyl groups
• Carbon groups attached to carbon chains are
named by using the prefix for the number of
carbons in the group + “yl”
• Ex: methyl = CH3 attached to any carbon chain
at any point. (see Table 20.2 on p. 709)
• Find longest carbon chain
• Number the carbons from the end closest to
the first alkyl group
• List alkyl groups in alpha order (disregarding
prefix), with carbon number they’re attached
to preceding group name
• If more than one of the same kind of alkyl
group exists, use di, tri, etc. prefixes in front of
that alkyl group’s name
• Ex: count the carbons in the longest chain:
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Eight carbons = octane
Methyl group on carbon #4
Ethyl group also on carbon #4
4-ethyl, 4-methyl octane
• HW:
– Text p. 713 Practice Problems (answers in green
section in back)
– Text p. 714 Practice problem
– Text p. 717 #8 a-d (watch out for bending carbon
chains!)