1. Models of the Atom Day 1

2. What is an atom? Why do we care about older models?

3. How would you measure the charge on an electron? http://www.youtube.com/watch?v=5A6ypp- 7S1Q http://www.youtube.com/watch?v=5A6ypp- 7S1Q

4. How would you measure the charge on an electron? Utilize its properties – Deflected by an electric field – Deflected by a magnetic field – Coulomb’s law- strength of force is related to charge and distance squared Overcome obstacle of size – Experimental set-up – Turns out that you can just make everything smaller

5. Millikan’s oil drop experiment http://www.wwnorton.com/college/chemistry /gilbert2/tutorials/interface.asp?chapter=cha pter_02&folder=millikan

6. Basis of Thomson’s Model Made before Millikan’s experiment Matter is neutral Electron’s are much smaller than atoms Atoms are ionizable- so there must be a positive and negative part (not just a billiard ball) Cathode rays /electron beams implied the presence of electrons No evidence of protons had been found

7. Thompson’s Model- Plum Pudding Dilute positively charged pudding Pudding embedded with electrons

8. Next time… What happens when you shoot positively charged particles at plum pudding atoms?