Year 7 Science · Unit 2 · Lesson 14
Challenge Worksheet
Learning Goals
Evaluate the claim
Someone claims…
"Radioactive isotopes are far too dangerous to use in medicine or archaeology. Any exposure to a radioactive isotope causes immediate harm to the human body, so scientists should never use them in hospitals or research labs. The risk always outweighs the benefit."
(a) What part of this claim is supported by science? (Hint: radioactive isotopes do emit radiation — is there any genuine risk?)
(b) Use carbon-14 dating as a specific counter-example. Explain how scientists use C-14 in archaeology without causing harm to people.
(c) Technetium-99m (Tc-99m) is a radioactive isotope injected into patients at hospitals like Sydney's Royal Prince Alfred to create bone scans that detect cancer or fractures. How does this use challenge the claim that "the risk always outweighs the benefit"?
1. In 2018, Australian archaeologists used carbon-14 dating to confirm that Aboriginal Australians have lived at Lake Mungo in New South Wales for at least 50,000 years. Explain, using the idea of isotope decay, why C-14 dating can give reliable age estimates for objects that old.
2. The claim says exposure to radioactive isotopes causes "immediate harm." What additional information or evidence would you need to properly evaluate whether that part of the claim is true or an overstatement?
Wrap Up
In one sentence, what was the main idea of this lesson?