Ap CHemistry Chapter Two Atoms & Elements

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

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

4. J. J. Thompson Metal electrodes Evacuated glass tube 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 • Cathode Ray Tube

5. Ernest Rutherford Gold Foil Experiment 1909 Nucleus small, dense Positive charge Atom mostly empty space Please follow this link, but there are more slides after this one http://videos.howstuffworks.com/hsw/23469-atomic-structure-the-rutherford-model-of-the-atom-video.htm

6. Robert Milliken 1868-1953 Oil Drop Experiment Measured charge on electron Like a perfume sprayer Gives droplets a charge Please follow this link http://video.google.com/videosearch? hl=en&q=oil%20drop%20experiment&ie=UTF-8&sa=N&tab=iv#

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 = atomic number 24 Z also = #protons Cr Average mass from isotopes 51.99 Atomic number gives atom its identity 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 1023 3 13 Li Al 6.941 This many grams = 1 mole 26.98 Different for each element But 1 mole = 6.022 x 1023 atoms, ions, molecules Always Diatomic H, N,O , and Halides N Need to double mass 14.0 1 mole = 28.0 g

10. The Periodic Law Mendeleev arranged by mass http://videos.howstuffworks.com/hsw/14740-simply-science-mendeleevs-table-video.htm Moseley arranged by atomic mass currently Please view the following 2 links http://videos.howstuffworks.com/hsw/5810-atomic-structure-periodic-law-video.htm http://videos.howstuffworks.com/hsw/5811-atomic-structure-modern-periodic-table-video.htm

11. Experimented with photographic plates& discovered radioactivity Henri Becquerel Named Becquerel’s discovery radioactivity Marie Curie Who discovered the electron & what experiment J.J. Thompson, Cathode Ray How did Thompson determine the electron was negative Bent in magnetic field What scientist demonstrated the existence of the nucleus & what experiment Rutherford, Gold foil small, dense, + charge, contributes the mass What else did Rutherford’s experiment show about the nucleus 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 diatomic hydrogen, nitrogen, oxygen and the halides Quiz yourself 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 % You’re smoking!!! Sorry--couldn’t resist