1. History of the Atom

2. Democritus (400 BC) Proposed that matter was composed of tiny, invisible particles. Gr. atomos

3. Aristotle Said that all substances are composed of four elements: Earth, Wind, Fire, and Water.

4. John Dalton (1803 AD) the first coherent atomic theory Matter is composed of small particles called atoms. All atoms of an element are identical. During chemical reactions, atoms are neither created nor destroyed, but are simply rearranged.

5. J.J. Thompson (1897 AD) Used cathode rays to calculate the atomic mass of atoms.

6. Cathode Ray Tube Experiment

7. Ernest Rutherford (1910 AD) alpha particles (He nuclei) were shot at a thin piece of gold foil. most of the particles passed through the foil with little or no deflection, some were deflected to a great degree.

8. Gold Foil Experiment

9. Isotopes

10. Radioactive Decay

11. C 14 Decay

12. Carbon Dating

13. Carbon Dating Video Click on the picture above to view.