topic 1a - atoms, elements, compounds and mixtures (10. the history of the atom) Flashcards
state the history of the atom in order
1) John Dalton described atoms as solid spheres
2) JJ Thompson concluded atoms were not solid spheres. Atoms had smaller negatively charged particles(electrons). theory cally plum pudding model. ball of positive charge with electrons stuck in it.
3) Ernest Rutherford conducted the alpha particle scattering experiment. Fired positively charged alpha particles at a thin sheet of gold. Expected most of the particles to pass straight through. Most did go through some were deflected more than expected and some were deflected backwards. As a result, Rutherford made the nuclear model. The tiny positively charged nucleus is in the centre. and a cloud of negative electrons but most of the atom was empty space.
4) Scientists realised the cloud of electrons would be attracted to the nucleus and therefore the atom would collapse, Niel Bohr, suggested the electrons were held in shells.
5) James Chadwick carried out an experiment which carried out experiment for neutral particles. Known as neutrons.
