PP 32: Alkanes
Drill: Draw the Lewis Dot Diagram for C6H8
Alkanes: Hydrocarbons containing only single covalent bonds or saturated hydrocarbons
•
•
All hydrocarbons with no multiple bonds end with the suffix -ane
Prefix: Alk- any length carbon chain
Organic Prefixes:
1 = meth2 = eth3 = prop4 = but5 = pentAlkanes:
1 = methane:
2 = ethane:
3 = propane:
4 = butane:
5 = pentane:
6 = hexane:
7 = heptane:
8 = octane:
9 = nonane:
10 = decane:
6=
7=
8=
9=
10 =
hexheptoctnondec-
CH4
C2H6
C3H8
C4H10
C5H12
C6H14
C7H16
C8H18
C9H20
C10H22
CH4
H3C-CH3
H3C- CH2-CH3
H3C- CH2- CH2-CH3
H3C- CH2- CH2- CH2-CH3
H3C- CH2- CH2- CH2- CH2-CH3
H3C- CH2- CH2- CH2- CH2- CH2-CH3
H3C- CH2- CH2- CH2- CH2- CH2- CH2-CH3
H3C- CH2- CH2- CH2- CH2-CH2- CH2- CH2-CH3
H3C- CH2- CH2- CH2- CH2- CH2- CH2- CH2- CH2-CH3
General Alkane Formula: CnH2n+2
Drill: Draw each of the following: C3H8
C3H6
C3H4
Name & give the molecular formula for alkanes with 1, 2, 3, 4, & 5 carbons:
Name each of the following:
C5H12
C3H8
C8H18
Saturated Hydrocarbon:
• A hydrocarbon with the maximum number of hydrogens possible
• A hydrocarbon with only single bonds
• All non-cyclic hydrocarbons are saturated
Unsaturated Hydrocarbon:
• A hydrocarbon with less than the maximum number of hydrogens possible
• A hydrocarbon with at least one multiple bond (double or triple bond)
•
Carbon Chains: Any continuously bonded group of carbons in a hydrocarbon is called a carbon chain.
Types of Formulas: (We will use butane as our example)
•
Molecular Formula: Simplest: (C4H10)
• Symbols of elements present & subscripts telling how many of each
•
Condensed formula: (bonds between Cs & Hs understood)
•
•
Bonds between Cs & Cs also understood: (CH3CH2CH2CH3)
•
Bonds between Cs & Cs shown: (CH3-CH2-CH2-CH3)
•
Repeating items in (): (CH3-(CH2-CH2)2-CH3)
Skeletal Formula: (Hs & bonds to Hs understood)
•
•
C-C-C-C
Complete structural formula: (All elements & bonds are shown as in Lewis Dot Diagrams)
HHHH
H-C-C-C-C-H
HHHH
•
Stick structures or minimal formulas: (Only bonds shown all Cs & Hs that are not part of a
functional group are understood)
•
•
•
Line ends & joints represent carbons
Hydrogens understood
Others draw
Alkane Shapes:
•
•
•
In 2 dimensions we draw bond s as 90o
The true bond s are 109.5o
Tetrahedral in shape
•
Draw each of the following in four diffenent ways:
•
•
Propane
butane
octane
methane
hexane
heptane
pentane
ethane