This key facts covers What Happens in Each Decay within Radioactive Decay for GCSE Physics. Revise Radioactive Decay in Atomic Structure for GCSE Physics with 15 exam-style questions and 6 flashcards. This is a high-frequency topic, so it is worth revising until the explanation feels precise and repeatable. It is section 4 of 14 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.
📚 What Happens in Each Decay
ALPHA DECAY (α):
- Nucleus emits an alpha particle (2 protons + 2 neutrons)
- Mass number decreases by 4
- Atomic number decreases by 2
- Element CHANGES (2 fewer protons = different element)
Example: ²²⁶₈₈Ra → ²²²₈₆Rn + ⁴₂α
BETA DECAY (β):
- A neutron turns into a proton (and emits an electron)
- Mass number stays the SAME
- Atomic number increases by 1
- Element CHANGES (one more proton)
Example: ¹⁴₆C → ¹⁴₇N + ⁰₋₁β
GAMMA EMISSION (γ):
- Nucleus releases excess energy as gamma ray
- Mass number stays the SAME
- Atomic number stays the SAME
- Element does NOT change (just loses energy)
- Often follows alpha or beta decay
Quick Check: In beta decay, the mass number stays the same. Why?
In beta decay, a neutron converts into a proton. One nucleon (neutron) is replaced by another (proton), so the total number of nucleons — and therefore the mass number — stays the same.
Practice questions for Radioactive Decay
An alpha particle consists of which particles?
Explain why alpha radiation is described as highly ionising but weakly penetrating.