Transcript 25-3: Hydrocarbons

25-3: Hydrocarbons
25-4: Saturated and
Unsaturated Hydrocarbons
Hydrocarbon
Organic molecule that contains only
hydrogen and carbon
Properties:
– All bonds are nonpolar, so molecule is
nonpolar
Are poor conductors
Have low density
Do not dissolve in water
– Found deep within the Earth as natural gas
and petroleum (fossil fuels)
Types of formulas
Molecular formula: gives symbols and numbers
of atoms present
– Ex: butane is C4H10
Structural formula: shows how the atoms are
bonded together in a two dimensional way
– Butane
Condensed structural formula: shows only how
carbon atoms are bonded
– Butane CH3CH2CH2CH3
Alkanes
Hydrocarbons with only single bonds
Names end in –ane
General formula: CnH2n+2
Is a saturated hydrocarbon; all carbon
bonds are filled to capacity with hydrogens
Alkane Series
Methane
Ethane
Propane
Butane
Pentane
Hexane
Heptane
Octane
Nonane
decane
CH4
C2H6
C3H8
C4H10
C5H12
C6H14
C7H16
C8H18
C9H20
C10H22
Branched Alkanes
1. Identify the longest continuous carbon
chain. This is the parent chain and is
named as a regular alkane.
2. Identify the shorter chain. Give this
chain a number (from the carbon that it is
bonded to) and name it as an alkyl group
(methyl, ethyl, propyl, butyl)
3. Examples
Conformations
Two structures that differ only by one or
more bond rotations
Examples
Structural Isomers
Two structures that have the same
molecular formula, but their atoms bond in
different orders.
Examples
Cycloalkanes
Cyclic hydrocarbons: hydrocarbons that
contain a carbon ring
If they contain all single bonds, then they
are cycloalkanes
Unsaturated Hydrocarbons
Contain at least one double or triple bond
between carbon atoms.
Alkenes
Contain at least one double bond.
General formula: CnH2n
In naming, name them just like alkanes,
just give a number to designate the
position of the double bond AND they end
in –ene.
Example: apples produce ethene gas as
they ripen.
Alkynes
Contain at least one triple bond.
General formula: CnH2n-2
In naming, name them just like alkanes,
just give a number to designate the
position of the triple bond AND they end in
–yne.
Ethyne is used in torches – also called
acetylene.
Benzene
Draw it.
Compounds that have a benzene ring in it
are called aromatic compounds (they
usually smell good!)
Examples of aromatic compounds include:
cloves, vanilla beans, and almonds.