Year 8 Science · Unit 2 · Lesson 21
Apply Worksheet
Learning Goals
1. Name the four stages of the chain from the lesson that links a scientific discovery to a change in society.
Match each discovery to what changed
Write the matching letter in the middle column. Each letter is used once.
| Discovery | Letter | What changed |
|---|---|---|
| Hall-Héroult process | A. Ammonia could be made cheaply for fertilisers. | |
| Silicon as a semiconductor | B. A material used in homes for decades was banned in Australia. | |
| Asbestos health evidence | C. A luxury metal became cheap enough for drink cans and foil. | |
| Haber process | D. Infections that were often deadly could be treated. | |
| Penicillin | E. An element found in ordinary sand became the base of computer chips. |
Cause and effect
Complete the chain for silicon. Fill the two empty boxes with the two middle stages of the chain, giving what happened to silicon at each.
Scenario: testing farm soil
In the 1950s, Alan Walsh (CSIRO, Melbourne) realised that atoms of each element absorb light at their own particular wavelengths. This became atomic absorption spectroscopy (AAS), now the standard way to measure trace metals. A farmer sends soil from five paddocks to a laboratory, which uses AAS to measure copper, a metal crops need in tiny amounts.
| Paddock | A | B | C | D | E |
|---|---|---|---|---|---|
| Copper (mg/kg) | 1.8 | 0.6 | 3.0 | 0.9 | 2.4 |
Source: sample laboratory results invented for this exercise. Guide for this exercise: soil below 1.0 mg/kg may need a copper fertiliser added.
2. (a) Which paddocks are below the guide value? (b) How many times more copper is in paddock C than in paddock B?
(a) (b) times
3. Before AAS, a farmer could not easily measure such tiny amounts of copper. Explain how Walsh’s understanding of atoms changed the way this farmer can use copper fertiliser.
4. Choose aluminium or lithium. Explain how improved scientific understanding changed the use of your substance, stage by stage through the chain, and name the application area it changed. Finish by explaining why the whole chain took decades.
Warm Up
1. Discovery; small-scale use; industrial production; societal change. [2 marks: all four; 1 mark for two or three]
Match each discovery to what changed
Hall-Héroult process → C; Silicon as a semiconductor → E; Asbestos health evidence → B; Haber process → A; Penicillin → D.
Cause and effect
Small-scale use: the semiconductor property is used to make transistors, tested in early devices to show they work. Industrial production: factories mass-produce transistors and integrated circuits (computer chips) cheaply. Accept any answer that shows testing in small devices, then large-scale manufacture.
Go Deeper
2. (a) B (0.6) and D (0.9). (b) 3.0 ÷ 0.6 = 5 times. [2 marks: 1 each]
3. Walsh understood that each element’s atoms absorb their own wavelengths of light, which let an instrument measure tiny amounts of one element in a sample. The farmer can now find out which paddocks are low in copper (B and D) and add copper fertiliser only there, instead of guessing or spreading it everywhere. Understanding atoms led to a new instrument, which changed how a substance is used. [3 marks: 1 the atom idea, 1 measuring tiny amounts, 1 targeted use of fertiliser]
Show What You Know
4. Marking guide (points expected), aluminium or lithium: 1 discovery: the Hall-Héroult process (1886) made extraction cheap; or 1970s battery research using lithium’s lightness and electrochemical properties; 1 small-scale use: aluminium tested in small uses; the first lithium-ion battery (1991); 1 industrial production: smelters such as Tomago; mass-produced batteries; 1 societal change: cans, foil and aircraft; phones and electric vehicles; 1 application area: materials or transport; electronics; 1 the delay: each stage needs testing, engineering, investment and factories, so the chain is not automatic (for aluminium it took nearly a century). [6 marks]
Common error to watch for: in the chain and Q4, treating the discovery as the change in society. Students should show that a discovery is only the first stage, and that scaling up takes decades.