Atomic Structure & Radioactivity is a core part of GCSE Physics. Revise the key concepts and common mistakes below, then lock them in with the free games.
Key concepts
IrradiationExposed to radiation from a source
ContaminationRadioactive material on/in something
Background radiationAlways present from environment
Half-life useChoose for medical or industrial use
PenetrationAlpha: paper. Beta: aluminium. Gamma: lead
SievertUnit of dose
AlphaHe nucleus (2p, 2n); mass 4, charge +2
Beta-minusElectron from neutron; mass 0, charge -1
GammaEM wave; no mass or charge
ActivityDecays per second; unit Bq
Half-lifeTime for activity to halve
Becquerel1 decay per second
Atom radiusAbout 1 x 10^-10 m
Nucleus radiusAbout 1 x 10^-14 m (1/10000 of atom)
What your exam board covers
Where Atomic Structure & Radioactivity sits in each exam board's specification. Tap a board to see what it lists.
AQAAtomic structureSpec 8463
Atoms and isotopes
Atoms and nuclear radiation
Hazards and uses of radioactive emissions and of background radiation (physics only)
Questions where students often pick the tempting wrong answer — make sure you know the right one:
What absorber is needed to stop beta radiation?✗ A sheet of paper — beta is only slightly more penetrating than alpha.✓ A few millimetres of aluminium (or similar thin metal sheet).
What did Rutherford's alpha-scattering experiment show about the atom?✗ It showed that atoms are solid spheres of positive charge with electrons embedded inside.✓ Most of the atom is empty space, with a tiny dense positive nucleus.
Which type of nuclear radiation is most ionising?✗ Gamma is most ionising because it can travel furthest and pass through almost anything.✓ Alpha radiation — large, doubly charged particles cause the most ionisation per unit distance.
Best for medical tracers:✗ alpha, short half-life✓ gamma, short half-life
After one half-life, what happens to an individual radioactive nucleus?✗ Every nucleus is guaranteed to have half-decayed after one half-life.✓ It has a 50 percent chance of having decayed — radioactive decay is random for any single nucleus.
Practise Atomic Structure & Radioactivity — free games
Test yourself with these quick revision games for this topic:
