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
G2 Science (Physics) · Topic 13
Read the complete lesson from top to bottom first. Pause for its examples and independent questions, then use a short topic check to decide what to practise again.
Before you begin
Build the idea in order
- Atomic nucleus and isotopes
- Random decay and radiation
- Background and half-life
- Applications and hazards
Lessons
G2 Radioactivity: Atomic Foundations and Nuclide Notation
Build a G2 model of the atom, distinguish proton and nucleon number, identify isotopes, and interpret nuclide notation accurately.
G2 Radioactivity: Nuclear Decay and Ionising Radiation
Explain random and spontaneous nuclear decay and compare alpha, beta-minus and gamma radiation by nature, ionisation and penetration at G2 depth.
G2 Radioactivity: Background Radiation and Half-Life
Use raw detector readings, consistent counting intervals and background correction to estimate half-life and remaining fractions.
G2 Radioactivity: Applications, Hazards and Protection
Match medical and industrial uses to radiation properties and distinguish irradiation, contamination and exposure controls.
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 when a nucleus decays; spontaneous means no trigger is required.
- Greater ionising effect usually accompanies lower penetration.
- Subtract background before a half-life calculation.
- Match source penetration and half-life to the use, then control time, distance and shielding.
Topic and syllabus information
Radioactivity is Topic 13 in K223 / K224 Physics component · 2027.
The lesson stays within G2 depth and includes the explanations, examples and practice needed for this topic.
Reviewed 9 Aug 2026
Course and syllabus information
- Course
- SEC G2 Science Physics component
- Edition
- SEC G2 Science Physics component 2027