1. Ap CHemistry Chapter Two Atoms & Elements Please do not memorize dates--I will never ask you for an exact one. However, you should have an idea (century-wise) of when events/discoveries happened.

2. Ben Franklin 1706-1790 Two types charge Positive & negative Charges balance If there is a positive charge, somewhere there is a negative charge of equal magnitude Still didn’t know about electrons But had electricity

3. Henri Becquerel 1852-1908 Uranium on photographic plates Emitted Rays Pals with Marie Curie She called it radioactivity Marie Curie Isolated polonium and radium

4. Cathode Ray Tube J. J. Thompson Evacuated glass tube Metal electrodes electric current produced glowing beam Bent by magnetic field Electrons Please to go the following link: http://www.youtube.com/watch?v=IdTxGJjA4Jw There are more slides

5. Ernest Rutherford Nucleus small, dense Gold Foil Experiment 1909 Positive charge Atom mostly empty space Please go to this web page, but there are more slides after this one http://www.mhhe.com/physsci/chemistry/essentia lchemistry/flash/ruther14.swf

6. Robert Milliken1868-1953 Measured charge on electron Oil Drop Experiment http://video.google.com/videosearch? hl=en&q=oil%20drop%20experiment&ie=UTF-8&sa=N&tab=iv#TF-8&sa=N&tab=iv# Please follow this link Like a perfume sprayer Gives droplets a charge

7. James Chadwick 1891- 1974 Neutron Alpha particles hit beryllium Beryllium released radiation Radiation hit wax & caused protons to come off

8. Atomic Number & Mass Cr 24 51.99 Z = atomic number also = #protons Atomic number gives atom its identity Average mass from isotopes Mass from neutrons and protons Relative mass Look at atom’s mass in relation to the mass of carbon

9. The Mole Latin: heap 1 mole = 6.022 x 10 23 Li 6.941 1 mole = 6.022 x 10 23 atoms, ions, molecules 3 Al 13 26.98This many grams = 1 mole Different for each element But Always Diatomic H, N,O, and Halides Need to double massN 14.01 mole = 28.0 g

10. The Periodic Law Mendeleevarranged by mass Moseley arranged by atomic masscurrently http://videos.howstuffworks.com/hsw/5810-atomic-structure-periodic-law-video.htm Please view the following 2 links http://videos.howstuffworks.com/hsw/5811-atomic-structure-modern-periodic-table-video.htm http://www.youtube.com/watch?v=JrK8mK_v1XY

11. Quiz yourself Experimented with photographic plates& discovered radioactivityHenri Becquerel Named Becquerel’s discovery radioactivityMarie Curie Who discovered the electron & what experimentJ.J. Thompson, Cathode Ray How did Thompson determine the electron was negativeBent in magnetic field What scientist demonstrated the existence of the nucleus & what experiment Rutherford, Gold foil What else did Rutherford’s experiment show about the nucleus small, dense, + charge, contributes the mass Who measured the charge on the electron & what experiment Millikan, Oil drop What is the atomic number of oxygen,how many electrons & protons 8,8,8 What is the mass of 1 mole of oxygen 32.0 g It is diatomic The mass of the elements are relative to what other element Carbon What elements are diatomichydrogen, nitrogen, oxygen and the halides Who is credited with the first periodic table & how was it arranged? Mendeleev, by mass Who changed Mendeleev’s arrangement, and how are the elements currently ordered? Moseley, by atomic number 100 %!!!