1. ATOMIC THEORY CHAPTER 11.1 IN HOLT TEXTBOOK

2. 460-370 BCE Ancient Greek Philosopher Matter divided into a smaller and smaller piece the uncuttable piece “atomos”

3. The Dalton Model The solid sphere model Atoms are seen as solid, indestructible spheres (like billiard balls) Explained how atoms join to make molecules and compounds Proposed 1 st atomic theory in 1803

4. JJ Thomson discovered electrons in 1897.

5. https://www.youtube.com/watch?v=GzMh4 q-2HjM JJ Thomson’s Cathode Ray Experiment

6. The Rutherford Model British Physicist who discovered the nucleus in 1908 Atom is mostly empty space Discovered the small, positive nucleus

8. The Bohr Model Danish scientist Proposed the Planetary Model in 1913 Electrons move in definite orbits or energy levels

9. An atom consists of a dense nucleus composed of protons and neutrons surrounded by electrons that exist in different clouds at the various energy levels. Electron Cloud Model (1920’s)