AtomicErnestRutherford5+181+2FREE!1+14+9Aristotle1+02+42+5Outsidenucleus1+4LowerEnergyLevels4+15Insidenucleus4+132+8ElectronJohnDaltonExcitedStateSpectrumNegativeGroundstate3+8Neutrons4+11MassnumberCompoundsElectronCloudModel4+124+142+71+3Centerof theatom5+192+65+16OctetRuleDemocritusNielsBohrProtonJ. J.Thompson5+173+9IsotopesValence4+105+15