What is Organic Chemistry?

Organic Chemistry is the study of carbon-containing compounds and their properties. Organic molecules are based on carbon atoms, which can form four bonds. This allows them to create a huge variety of structures, including chains, rings, and complex 3D shapes.

Key Concepts in Organic Chemistry:

1. Hydrocarbons: Hydrocarbons are compounds made up only of hydrogen and carbon atoms. There are two main types:
   • Alkanes: Saturated hydrocarbons (single bonds only). General formula: CₙH₂ₙ₊₂. Example: Methane (CH₄).
   • Alkenes: Unsaturated hydrocarbons (contain at least one double bond). General formula: CₙH₂ₙ. Example: Ethene (C₂H₄).
2. Crude Oil and Fractional Distillation: Crude oil is a mixture of hydrocarbons. It can be separated by fractional distillation, which works because different hydrocarbons have different boiling points. The process separates crude oil into fractions like petrol, diesel, and kerosene.
3. Combustion:
   • Complete combustion occurs when a hydrocarbon burns in plenty of oxygen, producing carbon dioxide and water.
     Example: CH4+2O2→CO2+2H2O\text{CH}_4 + 2 \text{O}_2 \rightarrow \text{CO}_2 + 2 \text{H}_2\text{O}CH4​+2O2​→CO2​+2H2​O
   • Incomplete combustion occurs when there isn’t enough oxygen, producing carbon monoxide (a toxic gas) or carbon (soot).
4. Functional Groups: Organic compounds are classified based on their functional groups, which determine their chemical properties. Key functional groups include:
   • Alcohols: −OH-OH−OH (hydroxyl group). Example: Ethanol (C₂H₅OH).
   • Carboxylic acids: −COOH-COOH−COOH. Example: Ethanoic acid (CH₃COOH).
5. Polymers: Polymers are large molecules made by joining many small molecules (monomers) together. Addition polymers are formed from alkenes through a process called polymerisation.

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