Radioactivity
Atomic structure, nuclide notation, random decay, radiation properties, background radiation, half-life, applications and hazards.
Learning goals
- Describe atomic composition
- Use proton number, nucleon number and isotope
- Use and interpret nuclide notation
- Explain random and spontaneous nuclear decay
- Describe alpha, beta-minus and gamma radiation
- Compare ionising effect and penetrating power
- Explain background radiation
- Use half-life in tables and decay curves
- State radioactivity applications and hazards
G3 Science (Physics) · Topic 16
Work through the lessons in order, then take the topic check to find the force models that need another look and practise them.
Before you begin
Build the idea in order
- Atomic nucleus and isotopes
- Random decay and radiation
- Background and half-life
- Applications and hazards
Lessons
Atomic foundations
Atomic structure, nuclide notation, random decay, radiation properties, background radiation, half-life, applications and hazards.
Decay and radiation
Atomic structure, nuclide notation, random decay, radiation properties, background radiation, half-life, applications and hazards.
Background radiation and half-life
Atomic structure, nuclide notation, random decay, radiation properties, background radiation, half-life, applications and hazards.
Applications, hazards and protection
Atomic structure, nuclide notation, random decay, radiation properties, background radiation, half-life, applications and hazards.
Check your understanding
Radioactivity topic check
Check the required topic capabilities and get focused practice for ideas that need another look.
What to remember
- Proton number identifies the element; nucleon number counts protons and neutrons.
- Random describes which nucleus decays and when; spontaneous means no external trigger is required.
- Alpha is most ionising and least penetrating; gamma is least ionising and most penetrating of the three.
- Subtract background count rate before using source data in a half-life calculation.
- Connect each application to a useful radiation property, then control exposure with time, distance and suitable shielding.
Topic and syllabus information
Radioactivity is Topic 16 in K326 / K327 Physics component · 2027.
The lesson and questions stay at the depth required for this course.
Reviewed 9 Aug 2026
Course and syllabus information
- Course
- SEC G3 Combined Science Physics component
- Edition
- SEC G3 Combined Science Physics component 2027