S4.11.1 For the adult
Unstable nuclei
Carbon 12 stays the same for ever, but carbon 14 does not. What is different about them?
What this chapter teaches
Some nuclei are unstable and may change by themselves, giving out radiation. This depends on the mix of protons and neutrons in the nucleus. Decay of a single nucleus is random and cannot be predicted, though a huge number of them behave steadily. Heat, pressure and chemistry do not change it.
Three questions to ask
There is no one right wording. Listen for the idea.
- Carbon 12 is stable and carbon 14 is not. What is different about their nuclei?
- Why can nobody say when one particular nucleus will decay?
- Would heating a radioactive sample make it decay faster? Why?
After the chapter, the learner can
- Explain why some isotopes are unstable and decay
- Explain that decay is random and cannot be predicted for one atom
What they copy into their notebook
A nucleus is stable or unstable. An unstable one decays and gives out radiation. The wrong mix of neutrons and protons, or a very large nucleus, can cause it. Decay is random. Heat does not change it.