2. Catalyst – October (4-5+2), 2009 1. Can people think that theories are correct even when they are not? How does this happen? 2. Do you think that the earth could be hollow? Why or why not?

3. Today’s Agenda  Catalyst  Atomic Theory Part 2  P.N.E and Atomic Math  Work Time  Exit Question

4. Today’s Objectives  SWBAT describe the evolution of atomic theory from 1898 to 1932.  SWBAT locate and describe protons, neutrons, and electrons in the modern atom.  SWBAT do atomic math!

5. Numero Cinco! - R. A. Millikan  Experiment: Millikan Oil Drop Experiment  When: 1909  Where: U.S.A!!!!

6. Millikan’s Oil Drop Experiment

7. Millikan’s Calculations – Whoa!

8. What were Millikan’s conclusions? I have most accurately measured the charge of an electron: -1.59 x 10 -19 Coulombs

9. What were Millikan’s conclusions? I have also most accurately measured the mass of an electron: 9.109 x 10 -31 kg

10. Numero Seis! - Ernest Rutherford  Experiment: Gold Foil Experiment  When: 1910  Where: Montreal

11. http://micro.magnet.fsu.edu/electromag/java/rutherford/

12. Gold Foil Experiment Explained  Alpha helium particles were shot through a piece of gold foil  Think aluminum foil but thinner and made out of gold!  Alpha helium particles are 8000 times more massive (bigger) than electrons, so Rutherford thought they would knock electrons out of the way, but they did not!

13. Remember! This is the current model of the atom (Thanks to Thomson)

14. More History Ernie’s (Rutherford) Big Adventure Thin Sheet of Gold Atoms

15. What were Rutherford’s conclusions?  Pretend you are Rutherford  As Rutherford, what conclusion would you make based on the data from the Gold Foil Experiment? = Hint: Positive repels positive, negative repels negative

16. - - -- +

17. What were Rutherford’s conclusions? Discovered the nucleus, a concentrated mass with positive protons! Nucleus is in the center of the atom The atom is mostly empty space

18. What’s this empty space idea?  The ratio of the size of the nucleus to the diameter of the orbits of electrons can be compared with placing a marble in the middle of a football stadium!

19. James Chadwick  Experiment – Beryllium Foil Experiment  When - 1932  Where – Cambridge Conclusions – Neutral radiation emitted; therefore, the nucleus contains another subatomic particle called the neutron (has a neutral charge)

20. - - -- ++ + + - - - - NUCLEUS NEUTRON ELECTRON PROTON

21. Atom Worksheet  Introduce yourself to Mista’ Atom!

22. Subatomic Particles Key Point #1: The three main subatomic particles are… Protons Neutrons Electrons

23. PROTONS (purple = positive)  Location: nucleus  Mass: 1.6726 x 10 -27 kg  Charge: 1+

24. NEUTRONS (no color = no charge)  Location: nucleus  Mass: 1.6749 x 10 -27 kg  Charge: neutral

25. ELECTRONS (in the red = negative)  Location: outside the nucleus  Mass: 9.1094 x 10 -31 kg  Charge: 1- The mass of 1,839 ELECTRONS = the mass of 1 NEUTRON! Electrons virtually have NO MASS!

26. Review of Subatomic Particles Subatomic Particle LocationMassCharge Protons Neutrons Electrons NUCLEUS OUTSIDE NUCLEUS 1.6726 x 10 -27 kg 1.6749 x 10 -27 kg 9.1094 x 10 -31 kg 1+ NEUTRAL 1-

27. Atomic Math!  Key Point #2: Atomic math helps us to find…  Number of protons  Number of neutrons  Number of electrons This helps us distinguish atoms from each other!

28. Atomic Math Bylaws 1. The atomic number of an atom is the same as the number of ___________________. 2. The number of electrons is equal to the number of _______________(in a neutral atom). 3. Atomic mass is equal to the number of _________________ plus the number of _________________. PROTONS NEUTRONS

29. Atomic Number pREVIEW of the Periodic Table Element Symbol Atomic Mass

30. Work Time  Complete the Atomic Structure worksheet  Check your Atomic Math!

31. Exit Question 1. What was Rutherford’s contribution to atomic theory? 2. Ruthenium has an atomic number of 44. It has an atomic mass of 101. How many protons, neutrons, electrons does a neutral atom of Ruthenium have?