Unstable Nuclei
⚛️ Unstable Nuclei
There are three main types of nuclear radiation, each with very different properties. They differ in what they are made of, how far they travel, and how much they ionise surrounding material.
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Penetrating power order: "Paper, Aluminium, Lead" — PAL. Alpha blocked by Paper, Beta by Aluminium, and Lead is needed for gamma (though it still gets through to some extent).
What changes in each decay:
- Alpha: A goes down 4, Z goes down 2 (loses a "he-4" helium nucleus)
- Beta: Z goes up 1, A stays same (neutron becomes proton: +1 proton)
- Gamma: Nothing changes in nucleus (just energy release)
Ionising vs penetrating: Think of a charging rhinoceros vs a laser beam. The rhino (alpha) does massive damage but stops quickly. The laser beam (gamma) pierces through everything but doesn't do much damage at each point.
Now try it yourself
Quiz · Question 1 of 15
An alpha particle consists of which particles?
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This topic in real past papers
Every real exam question we've found on radioactive decay, with a full worked answer.