* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project
The Parts of an Atom J.J. Thomson • He experimented with cathode ray tubes • He passed electricity through the tube and discovered the first subatomic particle – the electron • He developed the plum pudding model of an atom Plum Pudding Model Robert Millikan • He determined that the electron has a negative charge • He determined the mass of the electron Ernest Rutherford • He proved the plum pudding model was incorrect with the gold foil experiment Gold Foil Experiment positive alpha particles • He discovered the nucleus of the atom! • The nucleus is the dense, positively charged center of the atom • He came up with the Nuclear Atomic Model Nuclear Atomic Model Nucleus Electron • Years later, Rutherford discovered the proton • proton = a positively charged particle inside the nucleus + nucleus proton James Chadwick • worked with Rutherford • discovered the neutron – a particle in the nucleus with the SAME MASS as a proton, but with NO charge (it’s neutral)! Modern Atomic Structure • spherically shaped • most of atom’s mass is in the nucleus (99.7%) • nucleus surrounded by negative electrons • Atoms have no charge (they are electrically neutral) because the number of protons is equal to the number of electrons - - + + + - 3 protons (+) 3 electrons (-) particle relative mass location charge – in space around nucleus – 9.11 x 10 proton p+ inside nucleus + 1.673 x 10 – 24 1 neutron n0 inside nucleus no 1.673 x 10 charge – 24 1 electron symbol e mass (g) *Electron has the least mass – 28 _1__ 1840 You Made It!!!