1. The Atom and its Structure You need iPads and/or Notebooks! Open eBackpack.

2. Important Vocabulary atom The smallest piece of an element that still represents that element. (p. 44) electron A negatively charged particle that occupies the space inside an atom outside the nucleus. (p. 46) nucleus The region in the center of an atom where most of the atom’s mass and positive charge is located. (p. 50)

3. Vocab Continued… Proton A positively charged particle in the nucleus of an atom. (p. 50) Neutron A neutral particle in the nucleus of an atom. (p. 51) Electron Cloud The region surrounding an atom’s nucleus where one or more electrons are most likely to be found. (p. 52)

4. The size of atoms The Size of Atoms Atoms are so small that they can be seen only through the most powerful microscopes. The scanning tunneling microscope (STM), which enabled scientists to see atoms for the first time, was not invented until 1981. However, scientists had been convinced of the existence of atoms and had known much about an atom’s structure well before then.  Image from a STM

5. Atoms and the Periodic Table Watch the video. Take notes about what you see in your interactive science journal! In the 19 th century, how many elements were believed to exist?

6. The Discovery of the Electron What was the first sub-atomic particle discovered? Who discovered it?

7. The discovery of the atomic nucleus Who discovered the atomic nucleus? What two particles had been discovered by 1932?

8. The Existence of Quarks What device aided in the discovery of new particles? Who discovered Quarks? Which two subatomic particles are made up of quarks?