1. Lesson 2.1 – Atomic Structure History of the Atom

2. Discovery of the Atom Timeline

3. Ancient Philosophers Democritus (460-370 bc) All matter is composed of individual atoms that are indivisible and solid Atoms move through empty space No experimentation was done

4. Ancient Philosophers Aristotle (384-322 BC) Disagreed with Democritus Didn’t believe in empty space Democritus' idea for the atom was ignored for over 2000 years

5. John Dalton (1768-1828) Dalton’s Theory (1808)  Matter is composed of extremely small indivisible particles called atoms

6. Dalton’s Theory Continued All atoms of a given element are identical, (size, mass, properties). Atoms of a specific element are different from those of any other element.

7. Dalton’s Theory Continued Atoms can’t be created, destroyed or divided

8. Dalton’s Theory Continued Atoms combine to form compounds

9. Dalton’s Theory Continued In a chemical reaction, atoms are separated, combined, or rearranged.

10. Dalton’s Theory Continued  *** These are almost all right – which one’s aren’t?