1. IAN page 37 Atomic History Main Ideas 1. Democritus (13) 2. John Dalton (14) 3. Atomic Theories 4. JJ Thompson (15) 5. Cathode Ray Objective Identify & Interpret Atomic History by using notes & diagrams on IAN pgs. 38-39 to write a Schafer summary including all of the main ideas.

2. A. Democritus (460-400 B.C.) all matter was made up of tiny pieces called "atomos"-- which is Greek for " that which cannot be broken down or further cut " Science went into a time of stagnation "the dark ages" 460 B.C. – 400 B.C. I. Theories about the Atom Aristotle (384 B.C.- 322 B.C) disagreed with Democritus, he proposed that matter was uniform throughout and not composed of smaller particles.

3. B. John Dalton (1766 - 1844) English scientist, proposed his atomic theories in 1808. 1766 - 1844

4. a. Elements are composed of tiny, discrete and indestructible particles called atoms. b. Atoms of the same element are identical. c. Atoms join with other atoms to make other substances. (Molecules)

5. Divide page 36 of your IAN into 3 ATOMIC MODELS

6. Solid Sphere Model

7. 1. In 1897 JJ Thomson (1856 – 1940) discovered that atoms contain tiny, negatively charged particles called electrons. Cathode Ray Experiments. (1856 - 1940)

8. Negatively Charged Beam of electrons Positively charge plates Vacuum Glass Tube

9. PLUM PUDDING MODEL Positive Matter Electrons

10. 2. The Electron has a mass of 9X10 -31 kg or one million millionth of the mass of a speck of dust..00000000000000000000000000000009 g

11. Positive Matter a. Thomson still did not identify how electrons moved around? b. Or where the positively charged particles were? (the charge of an atom is neutral) Electrons