Lesson 6: Polymers: Addition Polymerisation & Materials
Demonstrating understanding of organic chemical structure, properties, and reactions for NCEA Level 2 Chemistry.
🎯 Ngā Whāinga Akoranga | Learning Intentions
Addition polymerisation mechanisms of alkene monomers (e.g., ethene to polyethene, propene to polypropene, chloroethene to PVC), repeating units, and environmental lifecycle impacts.
Draw structural formulas for monomers and polymer repeating units, explain physical property changes from monomer to polymer, and evaluate kaitiakitanga challenges of synthetic plastic waste.
🎥 Media Anchor & Pedagogical Scaffold
Addition Polymerisation & Polymer Structure
Video Clip: GCSE Chemistry — Addition Polymers and Polymerisation (2026/27 exams) | Cognito (Runtime: 7m 11s).
🧠 1. Before Viewing (Activate & Predict)
How do small reactive gas molecules (monomers) link together to form tough, durable solid plastics (polymers)?
👁️ 2. During Viewing (Watch With a Job)
- Definition: in your own words, what is a polymer? What is a monomer, and what must a monomer have to undergo addition polymerisation?
- Draw: sketch the polymerisation of ethene into poly(ethene). Show 3 monomer units combining and draw the repeating unit of the polymer.
- Properties: the video links polymer structure to properties. Explain why poly(ethene) is flexible but NOT suitable for very high-temperature applications.
🗣️ 3. After Viewing & Kaiako Move (Process & Apply)
Kaiako Move: Connect synthetic polymer persistence with kaitiakitanga taiao and local NZ microplastic research in marine ecosystems.
Immediate Task: Complete Section 6 of your Organic Portfolio: Monomer-to-Polymer Drawing Sheet & Environmental Impact Analysis.
⚡ Whakaoho | Do Now: Organic Recall Challenge (10 mins)
Same reaction, different plastic. Polyethene, polypropene and PVC are all made by the same kind of reaction from three different alkenes.
Two minutes: draw ethene. Now draw three of them joined in a row with no atoms left over. What had to happen to the double bond to make that possible? Write it in one sentence — that sentence is addition polymerisation.
📖 Activity 1: Core Reaction Mechanism & Structure Analysis (25 mins)
Monomer ↔ repeating unit (15 min). Given four monomers, draw the repeating unit of each polymer, with the bonds shown continuing at both ends. Then work backwards: given two repeating units, identify the monomer that made them. Watch the substituents — that is where the marks are.
Find out, don't guess (10 min). Bring or find three plastic items. Look up the recycling code on each and what polymer it stands for — look it up, do not recall it — then match each to its monomer. Discuss: your local council accepts some of these and not others. Using structure, suggest why some plastics are easier to remelt and reuse than others.
📝 Activity 2: Level 2 Chemistry Portfolio Task & Merit/Excellence Scaffolding (20 mins)
Organic Portfolio — Section 6. Submit: (1) four monomer → repeating-unit conversions; (2) two reverse conversions; (3) a short evidence-based paragraph on one plastic your council does or does not accept, citing where you found the recycling information.
🏫 Kaiako Planning & Pedagogy Notes
NCEA Level 2 Alignment: Direct preparation for NCEA Level 2 Chemistry (External) (Demonstrate understanding of the properties of selected organic compounds). Emphasise linking observations and reagents to molecular structure for Merit/Excellence grades.