IGCSE›Edexcel IGCSE Physics›Mind mapsProperties of RadiationEdexcel IGCSE Physics: Mind mapStudy pack PDFAlso for this subtopic:Revision notesFlashcardsSubtopic testCover factsAtomic structureNucleus of protons and neutronsAtomic number = number of protonsMass number = protons + neutronsIsotopes: same protons, different neutronsTypesAlpha: helium nucleus, 2 protons + 2 neutronsBeta: fast-moving electronGamma: electromagnetic radiationNeutron: ejected from the nucleusEmission is randomPenetrationAlpha stopped by paperBeta stopped by few mm of aluminiumGamma reduced by lead or thick concreteMore ionising → less penetratingRadiationnuclei and decayα\alphaαβ\betaβγ\gammaγDetectingGeiger-Muller tube counts radiationPhotographic film darkens on exposureSubtract background radiation from readingsDecay changesAlpha: mass −4, atomic number −2Beta: mass same, atomic number +1Gamma: no change to eitherEquations must balance both numbers88226Ra→86222Rn+24He^{226}_{88}\text{Ra} \rightarrow {}^{222}_{86}\text{Rn} + {}^{4}_{2}\text{He}88226Ra→86222Rn+24HeExam tipsBalance mass number and atomic number separatelyLink ionising power and penetration as an inverseSubtract background in the penetration practical