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Structure and Naming of Alkanes and Cycloalkanes
Structure and Naming of Alkanes and Cycloalkanes
Structure and Naming of Alkanes Alkanes are hydrocarbon that have only sp3 carbons and hydrogens.
Each carbon atom in the molecule is surrounded by single covalent bonds. Each
carbon in an alkane is connected to four atoms in a tetrahedral geometry. Due
to this geometry and the small diffence in electronegativity between hydrogen
and carbon, alkanes are non-polar molecules. The general molecular formula
for alkanes is:
CnH2n+2
where n = number of carbon atoms in the alkane molecule
Below is listed the names of alkanes that have all the carbon atoms connected
in a continuous chain. The continuous chain does not mean that the carbons
are in a straight line. These molecules have bond angles of ~109.5o and
are free to rotate about any of the single bonds.
Alkanes: CnH2n+2
Name
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Molecular Formula
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Chemical Structure
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Space-Filled Drawing
(Click for large view)
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methane
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CH4
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ethane
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C2H6
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propane
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C3H8
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butane
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C4H10
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pentane
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C5H12
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hexane
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C6H14
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heptane
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C7H16
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octane
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C8H18
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noname
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C9H20
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decane
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C10H22
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Structure and Naming of Alkanes
Like simple alkanes, cycloalkane are also hydrocarbon that have only sp3 carbons
and hydrogens. However, these hydrocarbons form rings. Cycloalkanes have the
general molecular formula of:
CnH2n
where n = number of carbon atoms in the cycloalkane molecule.
The smallest cycloalkane is cyclopropane. Cyclopropane has a large angle strain
since the bond angle is 60o instead of the preferred bond angle
of 109.5o. Cyclobutane has a bond angle of 90o and cyclopentant
has a bond angle of 108o. All of the carbons lie in the same plane
iin these first three molecules. Beginning with rings of cyclohexane and larger,
the bond angles have the preferred 109.5o bond angle since the all
of the carbons are no longer in the same plane.
Cycloalkanes: CnH2n
Name
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Molecular Formula
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Chemical Structure
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Space-Filled Drawing
(Click for large view)
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cyclopropane
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C3H6
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cyclobutane
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C4H8
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cyclopentane
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C5H10
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cyclohexane
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C6H12
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cycloheptane
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C7H14
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cyclooctane
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C8H16
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