2.  We will be creating a timeline as a class.  Each group will be given a specific year or event. Using a computer, your task, as a group:  Determine what significant event in/related to nuclear physics occurred in that year (or which year the event occurred)  Determine which scientist(s) were involved  Be prepared to present a BRIEF summary of the event (you are not expected to understand/have details…those will come later!)  You will have 15 minutes max to complete this task!  Following your brief presentation, you will fill in the class timeline with your information

3.  Two distinct models of the structure of an atom:  1897-1904: JJ Thomson  1909-11: Ernest Rutherford  Use the resources provided to create a detailed, labeled set of illustrations to compare these two models of atomic structure  1 Poster per group  Diagrams, labels, and caption describing the model are all required. Due in 20 minutes.

4.  An atom is a mixture of positive and negative charges Image from: http://abyss.uoregon.edu/~js/21st_century_science/lectures/lec11.htmlhttp://abyss.uoregon.edu/~js/21st_century_science/lectures/lec11.html

5. Gold-Foil Experiment:  Very thin gold foil  Focused a beam of Helium nuclei  Observed the result of colliding the He nuclei with the Gold foil http://bhs.smuhsd.org/science-dept/marcan/apchemistry/structure_ML_MD.html

6.  Expected Results:  Positive Helium Nucleus would pass straight through the gold foil or only be slightly deflected…  Actual Results:  Most particles DID pass straight through with little to no deflection…  However: Several had unexpectedly large deflection angles!

7. Ernest Rutherford—several years after the Gold Foil Experiment

8.  Atoms have a dense, positively charged center (later called the nucleus) and the electrons must be in the space surrounding the nucleus  Completely different model than Thomson’s “Plum Pudding” model

9. Image from: http://abyss.uoregon.edu/~js/ast123/lectures/lec04.htmlhttp://abyss.uoregon.edu/~js/ast123/lectures/lec04.html

10.  Massive, positively charged nucleus  Electrons orbited much like planets around the Sun  The Coulombic (electrostatic) force of attraction between the positive protons and the negative electrons kept the electrons in orbit