Democritus & Aristotle/ John Dalton

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

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*

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

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

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*

Aristotle • Diagram of Aristotle's theory

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

Dalton's Theories • “Dalton's Atomic Theory” • Atoms of a specific element are different from those of a different element.

• Matter is composed of extremely small particles called atoms.

• Different atoms combine in simple whole-number ratios to form compounds.

• Atoms are indestructible and indivisible.

• In a chemical reaction, atoms are separated, combined or rearranged • Atoms of a given element have the same size, mass, and chemical properties.

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