1. Democritus & Aristotle/ John Dalton

2. Democritus Democritus was alive 460 B.C. - 370 B.C. Was a Greek philosopher He had no formal education and learned from his travels through out Greece

3. Democritus's Theory hypothesized that all matter (plus space and time) is composed of tiny indestructible units, called atoms. His beliefs were amazingly ahead of his time, but he could not answer what holds atoms together and therefore lost credibility *No Experiment*

4. Democritus Matter in empty space that has a different appearance Atoms determine properties

5. Aristotle Lived in 384 B.C. - 322 B.C. Was one of the most influential Greek philosophers Was educated at the Plato academy in Athens for nearly 20 years

6. Aristotle's Theory Belief: rejected Democritus' atomic theory, and he especially didn't agree with the theory that atoms more through empty space, because he didn't believe empty space exists. He was supported or considered more credible than Democritus because he already had a good reputation He did not believe that atoms exist but that matter is made of earth, fire, air and water *No experiment*

7. Aristotle Diagram of Aristotle's theory

8. John Dalton (1766-1844) ‏ English school teacher From the UK School - Pardshow Hall (a Quaker school) ‏

9. Dalton's Theories “Dalton's Atomic Theory” Matter is composed of extremely small particles called atoms. Atoms are indestructible and indivisible. Atoms of a given element have the same size, mass, and chemical properties. Atoms of a specific element are different from those of a different element. Different atoms combine in simple whole-number ratios to form compounds. In a chemical reaction, atoms are separated, combined or rearranged

10. Dalton's experimental design Law of definite proportions And that all matter is the same