Organic Chemistry
Hydrocarbons
Organic Chemistry
• The study of the compounds
that contain the element carbon
• Are numerous due to the
bonding capability of carbon
Carbon
• Is able to form 4 covalent bonds
• can form single, double, or triple covalent
bonds
• makes possible a large number of
compounds
Organic Compounds
• Extensive in nature
• more numerous than inorganic compounds
Major sources of raw materials from
which organic chemicals are obtained
• Petroleum
• coal
• wood
• animal sources
Characteristics of organic
compounds
• Generally insoluble in water (are
generally nonpolar)
• dissolve in nonpolar solvents
(benzene)
– organic compounds that are somewhat
polar will dissolve in water
• Are generally nonelectrolytes
• generally low melting points
– nonpolar - intermolecular forces weak
• slower reactions than those involving
inorganic compounds
– have strong covalent bonding within the
molecule
Bonding
• Forms compounds by covalent bonding
• C atom has 4 valence electrons forms 4
covalent bonds
• are spacially directed toward the corners of
a regular tetrahedron
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—C—
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Can share electrons with other C
atoms
 2 adjacent C atoms can share 1,2, or
3 pairs of electrons
 compounds are molecular in structure
 covalent bond represent by “ — “
(bond line) represents one pair of
shared electrons

Types of formulas
• STRUCTURAL FORMULA
– Formula showing bonding
• CONDENSED STRUCTURAL
FORMULA
– leave out some bonds and/or atoms from
the structural formula
• Page 746
• examples in table
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molecular formula
complete structural formula
condensed structural formula
more condensed structural formula
carbon skeleton
Isomers
• Have same molecular formula but
different structures
• example
– propanol CH3CH2CHO
– acetone CH3COCH3
• both have molecular formula
C3H6O
• As the number of atoms in the
molecule increases, the
possibility of more spatial
arrangements increases (more
isomers)
Saturated compounds
• Organic compounds in which carbon
atoms are bonded by the sharing of a
single pair of electrons. Are all single
bonds (one pair shared)
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• —C—C—C—C—C—
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Unsaturated compounds
• Contain 2 adjacent carbon atoms bonded
by the sharing of more than one pair of
electrons
• double bond > C = C <
• triple bond — C = C —
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(add third bond line please)
Hydrocarbons
• Organic compounds
that contain only
hydrogen and carbon
Homologous series of
hydrocarbons
• Groups having related
structures and properties
• each member of a series
differs from the one before it
by a common amount
• As members of a series increase in
molecular size, boiling point and
freezing point increases due to
Van der Waal’s Forces (force that
holds nonpolar molecules together)
Alkanes
• Series of saturated hydrocarbons
having the general formula:
•
CnH2n+2
• also called methane series or paraffin
series
• Alkane series begins showing
isomerism at butane (C4H10)
• Straight-chain alkanes - contain any
number of carbon atoms, one after
another, in a chain
• Page 745
• Must memorize the
prefixes - tells you how
many carbon atoms are
in the compounds
METHANE CH4
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H
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H—C—H
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H
ETHANE C2H6
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H H
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H—C—C—H
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H H
PROPANE C3H8
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H H H
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H— C — C — C — H
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H H H
BUTANE C4H10
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H H H H
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H—C—C—C—C—H
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H H H H
PENTANE C5H12
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H H H H H
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H—C—C—C—C—C—H
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H H H H H
• Page 747
• Sample problem 25-1 (done for
you)
• Practice problems
– change to six and seven carbons
SUBSTITUENTS
• An atom or group of atoms that can
take the place of a hydrogen atom on a
parent hydrocarbon molecule
• The halogens and groups of atoms
including C, H, O, N, S, or P may take
the place of a hydrogen atoms
• A hydrocarbon
substituent is called an
alkyl group can be one
carbon or several
carbons long
• examples:
• methyl CH3—
• ethyl
CH3CH2 —
• propyl CH3CH2CH2
• Alkyl group consists of an
alkane with one hydrogen
removed
• alkyl groups sometimes called
radicals
• Are named by removing the -ane
ending from the parent
hydrocarbon name and adding yl
• page 748 Answer red dot
question
• Page 748-749
• branched chain alkane - alkane with
one or more alkyl groups
• IUPAC SYSTEM FOR NAMING
BRANCHED CHAIN ALKANES
• follow in text #1-6
• Page 749 Sample Problem 252
• Practice problem 3
• Page 750 Practice Problem 4
• Can also reconstruct the structural
formula by following the rules on
page 750
• Sample problem 25-3
• practice problem 5
• Pg. 751 Practice problem 6
Unsaturated hydrocarbons
• ALKENES
– contain one double bond
between adjacent carbons
• page 754 look at structures
• Ethene (ethylene)
• propene (propylene)
• butene
• pentene
• and so on……..
Naming alkenes
• Locate the longest chain that
contains the double bond
– that is the parent alkene
• use that root name plus ene ending
• number the chain so that the
carbons with the double bond get the
lowest numbers
• Substituents names the same way
as for alkanes
• use a number to indicate the
location of the carbon that has
the double bond
ALKYNES
• Contain a triple bond between 2
carbons
• not plentiful in nature
• ethyne (acetylene)
• page 753 look at table 25.2
Isomerism
• Structural isomers
– Compounds that have the same
molecular formula but different
molecular structures
• examples on page 754
• butane and 2-methylpropane
• Have different physical
properties (melting point, boiling
point) In general, the more
highly branched in structure, the
lower its boiling point)
• also have different chemical
properties
Geometric isomers
• Differ only in the geometry of
their substituted groups
• trans configuration - the
substituted groups are on the
opposite side of the double bond
• Cis configuration - the
substituted groups are on the
same side of the double bond
• example on pages 754-755
• answer pink question #2
Stereoisomers
• Molecules of the same molecular
structure that differ only in the
arrangement of the atoms in space.
• Page 755 example
• page 756 samples and practice