Year 8 Science · Unit 2 · Lesson 19

How Discovery Changed the Uses of Substances

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Learning Goals

Apply lesson knowledge to explain a real-world case where poor understanding led to harm.
Trace a cause-and-effect chain from scientific discovery through to societal change.
Evaluate the connection between understanding a material's properties and the applications that become possible.

Warm Up

Real-world context

From 1917, factories in the United States hired young women to paint watch dials with a radium-based luminous paint called "Undark." Workers were instructed to shape their brushes to a fine point using their lips. By the early 1920s, many workers, known as the Radium Girls, had developed severe jawbone decay, anaemia and other radiation-related illnesses. Scientists eventually connected the illness to chronic radium ingestion. The resulting legal cases forced companies to acknowledge radiation hazards, and new workplace safety laws were introduced. Today, radium is used only in tightly controlled medical and industrial settings.

(a) Explain what property of radium was not understood by employers or workers in 1917. What were they missing that would have changed their behaviour?

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(b) How did improved scientific understanding of radiation change the way radioactive substances are used today? Give at least one specific example in your answer.

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Your Turn

Because… chain

Fill in the missing steps in the chain below. Each box leads to the next. The given steps are shaded, write your answers in the empty boxes.

Silicon is found abundantly in sand (SiO₂), one of Earth's most common compounds

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In the 1940s, scientists discovered that purified silicon could act as a semiconductor, conducting electricity only under certain conditions

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The transistor was invented, replacing bulky, fragile vacuum tubes in electronic devices

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Billions of transistors were eventually etched onto a single silicon chip (integrated circuit)

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Overall outcome:

Show What You Know

1. Teflon (PTFE) was discovered accidentally in 1938 when a scientist was trying to make a new refrigerant. Its useful properties, non-stick, heat-resistant, chemically inert, were later identified. How does this show the link between understanding a substance's properties and developing useful applications?

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2. A scientist discovers that a new plastic compound is incredibly light and strong. Explain the steps that would need to occur before this discovery leads to widespread societal use. Use what you know about the discovery-to-use chain.

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Wrap Up

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