Honors Chemistry
Mrs. Klingaman
Ch. 25
Organic Chemistry:
Alkanes,
Alkenes,
Alkynes,
&
Branched
Chains
Name: ___________________________
Mods: _____________
The Basics

Organic chemistry deals with compounds that contain ________________. Carbon has the
ability to form ___________ ______________. Without this property, large biomolecules such
as proteins, lipids, carbohydrates, and nucleic acids could not form.

Hydrocarbons are organic compounds that contain only _____________ and _____________.
The four basic types of hydrocarbons are alkanes, alkenes, alkynes and aromatic
hydrocarbons.
Contain:
VSEPR Geometry
Saturated or
Unsaturated?
Bond Length
Bond Strength
alkane
alkene
alkyne
Properties of Alkanes

Expressing an alkane using its Lewis structure (structural formula) is not a convenient method.
Instead, the _________________ formula is often given by showing each carbon in the chain,
followed by the number of hydrogen atoms attached to each separate carbon.

o
Structural Formula:
o
Condensed Formula:
The only IMF’s present are _____________ ________________ ______________. The
strength of the LDF’s increases with increasing ____________ and number of
__________________ in the chain. Therefore, boiling point ________________ with
increasing IMF’s.

________________ are compounds that have the same molecular formula, but their atoms
are bonded in a __________________ __________________ order. The only difference in
isomers is the way in which the carbons are ________________.

In branched-chains, __________________ groups are one or more carbons that are attached
to the main chain/parent chain (they take the place of what would normally be a __________).
Organic Nomenclature

There are three parts to a compound name for a hydrocarbon:
1)
The _________ tells how many carbons are in the longest continuous chain.
Number of Carbons
2)
Base Name
Number of Carbons
1
6
2
7
3
8
4
9
5
10
Base Name
The _____________ tells what type of compound it is (what functional group/family it is).
Family/Functional Group
Suffix Name
3)
The ________________ tells us what substituent groups are attached to the chain
(only used when the chain is branched- a prefix is NOT necessary for straight
chain alkanes). For prefix names, ______ is added to the base number of carbons
in the substituent group to get the prefix name.
Number of Carbons
Prefix Name
Number of Carbons
1
6
2
7
3
8
4
9
5
10
Prefix Name
Naming Straight Chain Alkanes:
Number of Carbons
1
2
3
4
5
6
7
8
9
10
Name =
Chemical Formula
Base + Suffix
(CnH2n+2)
IUPAC Rules for Naming Branched Chain Alkanes
Example:
1) Find the longest continuous chain of carbons in the molecule. This is the parent structure.
The parent structure in the example above is: ___________________________________.
2) Number the carbons in the main chain sequence. Start at the end that will give the groups
attached the smallest numbers. Number the parent chain in the example above.
3) Any carbon(s) that branch off of the parent chain are called substituent groups. Numbers are
needed to identify the position of each substituent group on the parent chain. These substituents
names and numbers become prefixes to the name of the parent alkane. In the example above,
the substituents and their numbers are: _____________________________________________
4) Use prefixes to indicate that the same substituent group appears more than once in a structure.
Common prefixes are di- (twice), tri- (tree times), tetra- (four times), and penta- (five times). In the
example above, there is a substituent group that appears more than once. Use prefixes to
indicate the number of times that the group appears in the example above: _________________
5) List the names of the alkyl substituents in alphabetical order but ignore the prefixes di-, tri-, and
so on. Place the groups from the example above in alphabetical order:
_____________________________________________________________________________
6) Use proper punctuation; commas are used to separate numbers while hyphens are used to
separate numbers and words. The name of the alkane is written as one word. Name the alkane
from the example above:
_____________________________________________________________________________
Name the following compound using the
IUPAC rules:
Name: ___________________________________________________________
Organic Nomenclature: Branched Alkanes with Substituents
Directions: Name the following branched alkanes according to IUPAC rules:
Drawing Alkane Structures
Directions: Draw structural formulas for the following alkane molecules:
Remember the following when drawing alkanes:




Carbons on the end of a chain always have three hydrogens attached.
Carbons in the middle of the chain always have two hydrogens attached.
Carbons that have one branched substituent group are also attached to one hydrogen.
Carbons that have two branched substituent groups attached do not have any hydrogens.
1)
propane
2)
2-methyl butane
3)
3-ethyl pentane
4)
2,3,5-trimethyl octane
5)
3-ethyl-2,2-dimethyl hexane
Organic Nomenclature: Alkenes and Alkynes
Directions: Name the following alkenes (double bonds) and alkynes (triple bonds):
Remember the following when naming alkenes and alkynes



The parent chain of an alkene ends in –ene; the parent chain of an alkyne ends in –yne
The parent chain should be numbered so that the double/triple bond has the lowest possible
number
When no number is given, the double/triple bond is always between the 1st and 2nd carbons
Drawing Alkene and Alkyne Structures
Directions: Draw structural formulas for the following molecules:
Remember the following when drawing alkanes:



All carbons need to have four covalent bonds around them in order to satisfy the octet rule
Carbons that are sharing a double bond many be bonded to two other things (carbons or
hydrogens)
Carbons that are sharing a triple bond can only be bonded to one other things (carbons or hydrogens)
1) ethene
2) butyne
3) 5-ethyl-3-octyne
4) 4,4-dimethyl-2-pentene
5) 2,3-diethyl-5-methyl-3-heptene