Year 9 Science · Unit 2 · Lesson 13

Naming and Representing Alkanes

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Learning Goals

Warm Up

Because… chain

Fill in the missing effects. Each step follows logically from the one before it.

The IUPAC naming system was adopted internationally in 1919 →
→
chemists worldwide follow the same prefix and suffix rules →
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no confusion arises between different languages or historical naming systems →
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a chemist in Sydney and one in Tokyo can communicate exactly about the same molecule.

Overall outcome:

Your Turn

Scenario

A student is given the condensed formula CH₃–CH₂–CH₂–CH₂–CH₃ and must identify its IUPAC name. The student then needs to predict its boiling point compared to propane (boiling point −42 °C), knowing that longer alkane chains have higher boiling points due to stronger intermolecular forces.

(a) Count the carbon atoms in CH₃–CH₂–CH₂–CH₂–CH₃ and write its IUPAC name. Show your reasoning.

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(b) Predict whether this compound's boiling point is higher or lower than propane's (−42 °C). Justify your prediction using the relationship between chain length and boiling point.

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Show What You Know

1. A compound has the molecular formula C₄H₁₀. Write its IUPAC name, its condensed structural formula, and identify what type of hydrocarbon it is.

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2. Explain the difference between a molecular formula and a condensed structural formula. Use octane (C₈H₁₈) as your example.

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Wrap Up

In one sentence, what was the main idea of this lesson?

HSCScience · Year 9 Science · Unit 2 · Lesson 13 · Apply Worksheet