Year 8 Science · Unit 2 · Lesson 08
Challenge Worksheet
Learning Goals
Evaluate the claim
Read the claim below carefully. It contains some accurate science alongside oversimplifications and logical flaws. Use your knowledge from this lesson to analyse it.
Someone claims...
"Radioactive isotopes are dangerous and should never be used in medicine. The radiation they emit can cause cancer, so using them to treat cancer or scan bones is contradictory and irresponsible. Natural elements without radioactive isotopes are always safer for the human body. Scientists should find a way to do all medical scans without using any form of radiation."
(a) What part of this claim is scientifically correct? Identify at least one accurate statement and explain why it is supported by the science you have learned.
(b) What is misleading or oversimplified in this claim? Identify at least two problems with the reasoning, using scientific ideas to explain why the claim is not fully accurate.
(c) What evidence or information would you need to properly evaluate whether the benefits of using radioactive isotopes in medicine outweigh the risks?
1. Technetium-99m (used in bone scans) and iodine-131 (used in thyroid cancer treatment) are both radioactive isotopes, yet they are used very differently in medicine. Using your knowledge of isotopes and their properties, explain why having different isotopes available gives doctors more flexibility in treatment, rather than being a problem.
2. Carbon-14 (Z = 6, A = 14) and nitrogen-14 (Z = 7, A = 14) have the same mass number but are completely different elements. A student says: "If they have the same mass number they must be closely related, maybe one turns into the other easily." Evaluate this statement using your knowledge of atomic structure. Is there any scientific basis to what the student said?
Wrap Up
In one sentence, what was the main idea of this lesson?