Organic Chemistry - Intro
A hydrocarbon is a compound containing carbon and
hydrogen only.
Hydrocarbons can be saturated or unsaturated.
• A saturated hydrocarbon has single bonds only.
• An unsaturated hydrocarbon contains multiple carbon-
to-carbon bonds.
A homologous series is a series of organic compounds with
the same functional group that would each successive
member differing by a -CH2- unit.
The simplest homologous series is the alkane. Alkanes
contain single carbon-to-carbon bonds.
They have the general formula: CnH2n+2
A functional group is the part of the organic molecule
responsible for its chemical reactions. In addition to hydrogen,
carbon can bond other elements, including oxygen, nitrogen,
and halogens. This results in the formation of molecules
containing different functional groups.
, Chemical Formulae
Molecular formula a formula that shows the number and
type of atoms of each element present in a molecule.
e.g. Ethanol, C2H6O
Empirical formula a formula that shows the simplest whole-
number ratio of atoms of each element present in compound.
e.g. Glucose has the molecular formula C6H12O6 and therefore
the empirical formula CH2O
General formula the simplest algebraic formula of the
member of a homologous series.
e.g. The general formula of the alkanes is CnH2n+2.
Displayed formula a formula that shows the relative
positioning of all the atoms in the molecule and the bonds
between them.
e.g. But-1-ene has the displayed formula…
Structural formula a formula showing the minimal detail for
the arrangement of atoms and molecule.
e.g. 2-methylbutane has the displayed formula…
the structural formula is… CH3CH(CH3)CH2CH3
Skeletal formula a simplified organic formula, with hydrogen
atoms removed from alkyl chains, leading just a carbon
skeleton and associated functional groups.
e.g. 2-methylbutane has the displayed formula…
the skeletal formula is…
, Nomenclature of Organic
Compounds
Hydrocarbons can be classified as:
• Aliphatic – containing carbon atoms joined together
in unbranched (straight) or branched chains.
• Alicyclic – containing carbon atoms joined together in
a ring that is not aromatic.
• Aromatic – containing one or more benzene ring.
There are three homologous series of aliphatic
hydrocarbons needed to be aware of.
• Alkanes – containing single carbon-to-carbon bonds.
• Alkenes – containing at least one double carbon-to-
carbon bond.
• Alkynes – containing at least one triple carbon-to-
carbon bond.
Naming aliphatic alkanes:
1) The stem of the name indicates the number of carbon
atoms in the longest continuous chain in the molecule.
2) A suffix is added after the stem to indicate functional
groups.
3) The prefix can be added before the stem, often to indicate
the presence of side chains or a functional group.
These sidechains are known as alkyl groups.
An alkyl group has a hydrogen atom removed from an
alkane parent chain. The name of the alkyl group is added
as a prefix to the name of the parent chain. Add numbers
before any alkyl group to show the position of the alkyl
group on the parent chain. The side chains are ordered
alphabetically.
A hydrocarbon is a compound containing carbon and
hydrogen only.
Hydrocarbons can be saturated or unsaturated.
• A saturated hydrocarbon has single bonds only.
• An unsaturated hydrocarbon contains multiple carbon-
to-carbon bonds.
A homologous series is a series of organic compounds with
the same functional group that would each successive
member differing by a -CH2- unit.
The simplest homologous series is the alkane. Alkanes
contain single carbon-to-carbon bonds.
They have the general formula: CnH2n+2
A functional group is the part of the organic molecule
responsible for its chemical reactions. In addition to hydrogen,
carbon can bond other elements, including oxygen, nitrogen,
and halogens. This results in the formation of molecules
containing different functional groups.
, Chemical Formulae
Molecular formula a formula that shows the number and
type of atoms of each element present in a molecule.
e.g. Ethanol, C2H6O
Empirical formula a formula that shows the simplest whole-
number ratio of atoms of each element present in compound.
e.g. Glucose has the molecular formula C6H12O6 and therefore
the empirical formula CH2O
General formula the simplest algebraic formula of the
member of a homologous series.
e.g. The general formula of the alkanes is CnH2n+2.
Displayed formula a formula that shows the relative
positioning of all the atoms in the molecule and the bonds
between them.
e.g. But-1-ene has the displayed formula…
Structural formula a formula showing the minimal detail for
the arrangement of atoms and molecule.
e.g. 2-methylbutane has the displayed formula…
the structural formula is… CH3CH(CH3)CH2CH3
Skeletal formula a simplified organic formula, with hydrogen
atoms removed from alkyl chains, leading just a carbon
skeleton and associated functional groups.
e.g. 2-methylbutane has the displayed formula…
the skeletal formula is…
, Nomenclature of Organic
Compounds
Hydrocarbons can be classified as:
• Aliphatic – containing carbon atoms joined together
in unbranched (straight) or branched chains.
• Alicyclic – containing carbon atoms joined together in
a ring that is not aromatic.
• Aromatic – containing one or more benzene ring.
There are three homologous series of aliphatic
hydrocarbons needed to be aware of.
• Alkanes – containing single carbon-to-carbon bonds.
• Alkenes – containing at least one double carbon-to-
carbon bond.
• Alkynes – containing at least one triple carbon-to-
carbon bond.
Naming aliphatic alkanes:
1) The stem of the name indicates the number of carbon
atoms in the longest continuous chain in the molecule.
2) A suffix is added after the stem to indicate functional
groups.
3) The prefix can be added before the stem, often to indicate
the presence of side chains or a functional group.
These sidechains are known as alkyl groups.
An alkyl group has a hydrogen atom removed from an
alkane parent chain. The name of the alkyl group is added
as a prefix to the name of the parent chain. Add numbers
before any alkyl group to show the position of the alkyl
group on the parent chain. The side chains are ordered
alphabetically.
