Chapter 20- Section 2- Group 2

1. Which German physicist discovered X rays?
2. What do we call a tiny particle that has a negative electrical charge?
3. Who discovered the electron?
4. How many times lighter than the smallest atom did J.J. Thomson say an electron is? ("? times")
5. What is the term used to refer to particles inside an atom?
6. What do we call the process in which atoms of uranium and radium constantly disintegrate and release energy on their own?
7. What are elements that disintegrate and release this energy called? ("? elements")
8. Which two French chemists discovered radioactivity in uranium and radium? (ex. "Tomer and Dan Ovadia")
9. Who proposed the idea of a nucleus in an atom?
10. What is the exteremely small and heavy core center of an atom called?

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1. Roentgen
2. electron
3. Thomson
4. 1,000 times
5. sub-atomic particles
6. radioactivity
7. radioactive elements
8. Pierre and Marie Curie
9. Rutherford
10. nucleus