Radioactive DecayEdexcel GCSE Physics: Flashcards
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What is an alpha particle equivalent to?
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- What is an alpha particle equivalent to?
- A helium nucleus (2 protons and 2 neutrons).
- What is a beta-minus particle?
- A fast-moving electron emitted from the nucleus.
- What is gamma radiation?
- Electromagnetic radiation emitted from the nucleus.
- Which type of radiation is stopped by a sheet of paper?
- Alpha radiation.
- Which type of radiation needs thick lead or concrete to significantly reduce it?
- Gamma radiation.
- Which radiation type is the most ionising?
- Alpha radiation.
- Describe β− decay in terms of what happens in the nucleus.
- A neutron becomes a proton, emitting an electron.
- Describe β+ decay in terms of what happens in the nucleus.
- A proton becomes a neutron, emitting a positron.
- How does alpha decay affect mass number and atomic number?
- Mass number decreases by 4; atomic number decreases by 2.
- How does β− decay affect atomic number?
- Atomic number increases by 1; mass number is unchanged.
- What is the unit of radioactive activity?
- The becquerel (Bq); 1 Bq = 1 decay per second.
- Define half-life.
- The time taken for half the undecayed nuclei in a sample to decay, or for activity to fall to half its value.
- Can you predict when an individual nucleus will decay?
- No — decay is random for individual nuclei, but half-life predicts the behaviour of large numbers reliably.
- A source has activity 600 Bq and half-life 2 hours. What is its activity after 4 hours?
- 150 Bq (two half-lives: 600 → 300 → 150).