Early Greek Theories :
Early Greek Theories 400 B.C. - Democritus thought matter could not be divided indefinitely. This led to the idea of atoms in a void.
Slide 3:
350 B.C - Aristotle modified an earlier theory that matter was made of four “elements”: earth, fire, water, air. Aristotle was wrong. However, his theory persisted for 2000 years.
2. John Dalton :
2. John Dalton 1800 -Dalton proposed a modern atomic model
based on experimentation not on pure reason. All matter is made of atoms.
Atoms of an element are identical.
Each element has different atoms.
Atoms of different elements combine in constant ratios to form compounds.
Atoms are rearranged in reactions.