IGCSE›Oxford AQA IGCSE Physics›Mind mapsAtomic StructureOxford AQA IGCSE Physics: Mind mapStudy pack PDFAlso for this subtopic:Revision notesFlashcardsSubtopic testCover factsThe atomSmall, central, positive nucleusNucleus holds protons and neutronsElectrons surround the nucleusRadius about 10−10 m10^{-10}\,\text{m}10−10mNucleus holds almost all the massAlpha scatteringAlpha particles fired at thin foilMost pass through → atom mostly empty spaceSome deflected or bounce back → dense positive nucleusReplaced earlier evenly spread modelsAtomic structurenuclear modelpneParticlesProton: mass 1, charge +1Neutron: mass 1, charge 0Electron: mass very small, charge −1Neutral atom: electrons = protonsIsotopes and ionsAtomic number = protonsMass number = protons + neutronsIsotopes: same protons, different neutronsCarbon-14 has 8 neutrons, carbon-12 has 6Lose electrons → positive ionGain electrons → negative ionExam tipsLink each observation to what it proves