AS Chemistry: Organic Chemistry
Introduction to Organic Compounds
Definition: Organic compounds are covalent compounds of carbon, originally obtained from plants
or animals.
Hydrocarbons: Organic compounds made up of only carbon and hydrogen.
Homologous Series: Groups of organic compounds with:
The same general formula.
The same functional group.
Similar chemical properties.
Members differing by a −CH2 − group.
Properties of Organic Compounds
Chain Length:
Shorter chains (fewer carbons) generally result in gases or liquids with lower boiling points.
Longer chains (more carbons) generally result in liquids or solids with higher boiling points.
The longer the chain, the higher the boiling point.
Branching:
Straight-chain compounds have higher boiling points than branched compounds with the same
number of carbons.
More branching leads to lower boiling points for the same number of carbons.
Types of Bonds:
Saturated: Contain only single bonds between carbon atoms. Alkanes are saturated. They are
generally less reactive.
Unsaturated: Contain at least one double or triple bond between carbon atoms. Alkenes and
alkynes are unsaturated. The double/triple bonds are reactive.
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, Naming Organic Compounds
Prefixes based on Carbon Number:
1 carbon: meth-
2 carbons: eth-
3 carbons: prop-
4 carbons: but-
5 carbons: pent-
6 carbons: hex-
Suffixes:
Alkanes: -ane
Alkenes: -ene
Alcohols: -ol
Carboxylic Acids: -oic acid
Functional Group Prefixes/Suffixes:
Halogens: chloro-, bromo-, iodo-
−NH2 (amino group): amino-
−NO2 (nitro group): nitro-
Naming Branched Chains:
Identify the longest continuous carbon chain (parent chain).
Number the carbons in the parent chain starting from the end that gives the substituents the
lowest possible numbers.
Identify and name the substituents (branches).
Use prefixes (di-, tri-, tetra-) to indicate multiple identical substituents.
Indicate the position of each substituent by its carbon number.
Example: For a compound with a six-carbon straight chain, two methyl groups on carbon 2, and
one methyl group on carbon 4, the name would be 2,2,4-trimethylhexane.
Formulas of Organic Compounds
Displayed Formula: Shows all atoms and all bonds.
Structural Formula: Shows the arrangement of atoms and bonds, often grouping hydrogens with the
carbon they are attached to.
Molecular Formula: Shows the total number of each type of atom in a molecule (e.g., C2 H6 O for
ethanol).
Skeletal Formula: Uses lines to represent carbon-carbon bonds. Carbons are assumed at the ends of
lines and at vertices. Hydrogens attached to carbons are not shown, but hydrogens on heteroatoms
(like O or N) are.
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Introduction to Organic Compounds
Definition: Organic compounds are covalent compounds of carbon, originally obtained from plants
or animals.
Hydrocarbons: Organic compounds made up of only carbon and hydrogen.
Homologous Series: Groups of organic compounds with:
The same general formula.
The same functional group.
Similar chemical properties.
Members differing by a −CH2 − group.
Properties of Organic Compounds
Chain Length:
Shorter chains (fewer carbons) generally result in gases or liquids with lower boiling points.
Longer chains (more carbons) generally result in liquids or solids with higher boiling points.
The longer the chain, the higher the boiling point.
Branching:
Straight-chain compounds have higher boiling points than branched compounds with the same
number of carbons.
More branching leads to lower boiling points for the same number of carbons.
Types of Bonds:
Saturated: Contain only single bonds between carbon atoms. Alkanes are saturated. They are
generally less reactive.
Unsaturated: Contain at least one double or triple bond between carbon atoms. Alkenes and
alkynes are unsaturated. The double/triple bonds are reactive.
1/9
, Naming Organic Compounds
Prefixes based on Carbon Number:
1 carbon: meth-
2 carbons: eth-
3 carbons: prop-
4 carbons: but-
5 carbons: pent-
6 carbons: hex-
Suffixes:
Alkanes: -ane
Alkenes: -ene
Alcohols: -ol
Carboxylic Acids: -oic acid
Functional Group Prefixes/Suffixes:
Halogens: chloro-, bromo-, iodo-
−NH2 (amino group): amino-
−NO2 (nitro group): nitro-
Naming Branched Chains:
Identify the longest continuous carbon chain (parent chain).
Number the carbons in the parent chain starting from the end that gives the substituents the
lowest possible numbers.
Identify and name the substituents (branches).
Use prefixes (di-, tri-, tetra-) to indicate multiple identical substituents.
Indicate the position of each substituent by its carbon number.
Example: For a compound with a six-carbon straight chain, two methyl groups on carbon 2, and
one methyl group on carbon 4, the name would be 2,2,4-trimethylhexane.
Formulas of Organic Compounds
Displayed Formula: Shows all atoms and all bonds.
Structural Formula: Shows the arrangement of atoms and bonds, often grouping hydrogens with the
carbon they are attached to.
Molecular Formula: Shows the total number of each type of atom in a molecule (e.g., C2 H6 O for
ethanol).
Skeletal Formula: Uses lines to represent carbon-carbon bonds. Carbons are assumed at the ends of
lines and at vertices. Hydrogens attached to carbons are not shown, but hydrogens on heteroatoms
(like O or N) are.
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