Introduction to Alkanes and Hydrocarbons
A comprehensive introduction to organic chemistry focusing on hydrocarbons, specifically the alkane homologous series. Students will learn how to name, draw, and predict the properties of alkanes, as well as understand their combustion reactions.
Learning objectives
- Identify and name the first four alkanes (methane, ethane, propane, butane).
- Explain the term 'homologous series' and apply the general formula for alkanes (CnH2n+2).
- Describe the trend in physical properties of alkanes as their chain length increases.
- Write balanced symbol equations for the complete combustion of alkanes.
Lesson plan (60 minutes)
Introduction · 5 min
Retrieval starter: Mind map everything students know about 'Carbon'. Discussion on fossil fuels.
Direct Instruction · 15 min
Teacher-led explainer: Introduction to Hydrocarbons and Alkanes using the 5-step script.
Guided Practice · 10 min
Worked Example: Drawing and naming the first four alkanes and calculating formulas.
Independent Practice · 20 min
Differentiated Worksheet completion: Students work through Support, Core, or Stretch tasks.
Assessment · 5 min
8-Question Multiple Choice Quiz to check understanding.
Plenary · 5 min
Self-marking and summary of the 'Monkey Eat Peeled Bananas' mnemonic.
Key vocabulary
- Hydrocarbon
- A compound containing only hydrogen and carbon atoms.
- Homologous Series
- A family of organic compounds with the same general formula and similar properties.
- Saturated
- A hydrocarbon containing only single covalent bonds.
- General Formula
- A formula representing the composition of a member of a homologous series (e.g., CnH2n+2).
- Viscosity
- The thickness of a liquid or its resistance to flow.
Core worksheet (first questions)
- An alkane has 4 carbon atoms. What is its molecular formula? Show your working.
- What is the main structural difference between an alkane and an alkene?
- Describe the trend in boiling points as the number of carbon atoms in an alkane increases. Explain why.
- Write a balanced symbol equation for the complete combustion of propane (C3H8).
Quiz (sample)
1. What is the definition of a hydrocarbon?
- A. A compound made of hydrogen and carbon atoms only.
- B. A mixture of different oils.
- C. A molecule with at least one double bond.
- D. A substance found only in plants.
2. What is the general formula for alkanes?
- A. CnH2n
- B. CnH2n+2
- C. CnHn+2
- D. C2nH2n+2
3. Which alkane contains exactly two carbon atoms?
- A. Methane
- B. Ethane
- C. Propane
- D. Butane
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