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Alkanes

Nomenclature:

Summary: 

Functional group suffix = -ane
Functional group prefix = alkyl-
  e.g. CH3CH3 = ethane
e.g. CH3CH2-  = ethyl 

More details on alkane nomenclature?

Physical Properties:
The low polarity of all the bonds in alkanes means that the only intermolecular forces between molecules of alkanes are the very weak induced dipole - induced dipole forces.  These forces are easily overcome.  As a result, in comparison with other functional groups, alkanes tend to have low melting and boiling points and very low solubility in polar solvents such as water (remember "oil and water don't mix" and the adage "like dissolves like").

Intermolecular forces in alkanes

Structure:
Consist of only sp3 hybridised C and H atoms connected by σ bonds.

Alkanes have a generic formula of CnH2n+2 (a relationship that also defines the maximum number of hydrogen atoms that can be present for a given number of C atoms).
Structures of the simple C1 to C4 alkanes are shown below in a variety of representations.
As the number of C atoms increases then other isomeric structures are possible.
 
methane
CH4
(b.pt. = -160oC)

ethane
C2H6
(b.pt. = -89oC)

propane
C3H8
(b.pt. = -42oC)

butane
C4H10
(b.pt. = -0.4oC)

Stability:

Reactivity: Want to try a few questions about alkanes ?

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 © Dr. Ian Hunt, Department of Chemistry, University of Calgary