INTRODUCTION TO ORGANIC CHEMISTRY
Organic Chemistry is the branch of chemistry which deals with the study of carbon and its compounds with exception of its oxides, carbonates, bicarbonates and carbides of metals.
Why Carbon Forms Many Compounds?
- Multiple bond formation: Carbon can form multiple bonds (double and triple bonds).
- Catenation property: The ability of carbon atoms to join with other carbon atoms of the same element and form long chains.
Importance of Organic Chemistry
It is important in life processes in the following ways:
- All organisms are made of organic compounds (e.g., proteins, lipids).
- Some organic compounds are used as medicines to treat illnesses.
- Used in textile manufacturing (natural or synthetic fibers).
- Source of energy (coal, petroleum, natural gas).
- Source of plastic products (containers, shoes, building materials).
Harmful Effects of Organic Compounds
| # |
Effect |
| 1 |
Chlorofluorocarbons (CFCs) contribute to global warming. |
| 2 |
Plastic materials are non-biodegradable and cause environmental pollution. |
| 3 |
Some insecticides harm animals, especially birds. |
Origin of Organic Compounds
(i) Prehistoric Sources
a) Coal: Formed from decayed plants and animals under layers of earth and rock over millions of years.
b) Crude oil & natural gas: Remains of marine plants and animals covered by sediment and transformed by bacteria.
(ii) Living Organisms
Plants produce complex organic compounds (e.g., starch, glucose) from simple inorganic compounds (CO2 and water).
(iii) Synthetic Sources
Organic compounds prepared in factories and laboratories (e.g., nylon, polyesters).
Terms in Organic Chemistry
Molecular formula: Shows actual number of atoms of each element in a compound.
Structural formula: Shows arrangement of atoms in a molecule (closed, condensed, or open forms).
General formula: Rule to calculate number of each atom type in a molecule.
Homologous series: Arrangement of organic compounds in order of increasing molecular mass.
Characteristics of Homologous Series
- Same general formula for all members
- Differ by -CH2 groups between members
- Same general preparation method
- Gradual change in physical properties
- Similar chemical properties
- Molecular weight difference of 14 between members
HYDROCARBONS
Compounds containing only carbon and hydrogen. Three families:
- Alkanes
- Alkenes
- Alkynes
Classification of Hydrocarbons
- Saturated hydrocarbons: Only single bonds between carbon atoms.
- Unsaturated hydrocarbons: Contain double (C=C) or triple (C≡C) bonds.
Properties of Saturated Hydrocarbons
- Undergo substitution reactions
- Do not decolorize bromine water
- Do not decolorize potassium permanganate (VII) solution
- Contain only single bonds
Properties of Unsaturated Hydrocarbons
- Undergo addition reactions
- Decolorize bromine water
- Decolorize potassium permanganate (VII) solution
- Contain double or triple bonds
ALKANES
Hydrocarbons with only single bonds between carbon atoms.
General formula: CnH2n+2 where n ≥ 1 (n = number of carbon atoms)