3. The structure of the atom The Ancient Greeks used to believe that everything was made up of very small particles. I did some experiments in 1808 that proved this and called these particles ATOMS: Dalton ELECTRON – negative, mass nearly nothing PROTON – positive, same mass as neutron (“1”) NEUTRON – neutral, same mass as proton (“1”)
5. The Atom Hydrogen Proton Electron Hydrogen has one proton, one electron and NO neutrons
6. The Atom Helium Electron Proton Neutron Helium has two electrons, two protons and two neutrons
7. Mass and atomic number -1 0 Electron 0 1 Neutron 1 1 Proton Relative Charge Relative Mass Particle He 2 4 MASS NUMBER = number of protons + number of neutrons SYMBOL PROTON NUMBER = number of protons (obviously)
8. The Atom Helium Electron Proton Neutron Helium has two electrons, two protons and two neutrons