AP Physics 2 / Unit 15: Modern Physics
15.8 Types of Radioactive Decay
Notes
- Alpha ($^4_2He$): mass number −4, atomic number −2.
- Beta-minus: a neutron becomes a proton; atomic number +1.
- Gamma: high-energy photon, no change in numbers.
- Half-life: time for half the nuclei to decay.
Practice
$^{238}_{92}U$ undergoes alpha decay. The product:
Mass −4, atomic number −2.
Beta-minus decay increases the atomic number by:
Neutron → proton.
After 3 half-lives, the fraction of a sample remaining:
$\displaystyle \left(\frac{1}{2}\right)^3$.
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