1. Atomic Structure Discovery of the electron –In 1897, JJ Thomson, an English physicist began studying atomic structure using a cathode ray tube (see right)

2. Thomson continued How did the experiment work?? Thomson deflected the cathode ray using an electrical field, resulting in the ray bending toward the positive pole, so……the ray had to be made of negative particles, called electrons

3. Thomson Conclusion But I thought the atom was neutral??? –It is!! Thomson knew that there must be a source of positive energy, but wasnt quite sure how it fit in. –So he developed the first model of the atom (on right) which he called Plum Pudding

4. Millikan and his oil drops Robert Millikan did some pretty neat experiments with oil drops to determine the mass of an electron to be 9.1 x 10 -31 kg.

5. Phase 2---Ernest Rutherford Rutherford was a student of Thomsons Weaknesses of Thomsons model Rutherford tries to expand Thomsons model to make it more complete

6. Rutherford continued In 1911, Rutherford designed an experiment to test Thomsons theory called the gold foil experiment (see right)

7. More Rutherford micro.magnet.fsu.edu/electromag/java/ruth erford

8. Enough Rutherford, already!! After all was said and done, Rutherfords final model of the atom looked something like this

9. Niels Bohr Knew Rutherfords model couldnt be completely correct or the electrons would crash into the nucleus So he proposed the electron energy level model

10. Finally! The Quantum Theory Bohrs model was very restrictive Are atoms REALLY that well-behaved? Louis de Broglie….wave or particles?? Walter Heisenberg and his uncertainty.. What is an orbital anyway??

11. Last, but not least!! So what does an atom actually look like?? (at least for now )