The Atomic Theory

The Atomic Theory

1. Empedocles

   • four-element system: earth, air, fire, water

2. Democritus

   • developed the first atomic hypothesis 

3. Aristotle

   • -opposed Democritus' idea -promoted 4-element system

4. Alchemists

   • -studied matter, experimenting with different chemical substances -used 4-element system

5. Boyle, Lavoisier, Priestly, Cavendish

   • found out that matter such as air and water were made of a mixture of pure substances

6. John Dalton

   • first atomic theory

7. Henrich Geissler

   • invented the sealed glass tube

8. William Crookes

   • cathode ray tube

9. J.J. Thomson

   • came up with the electron and the plum pudding model

10. Ernest Rutherford

    • came up with the nucleus

11. Niels Bohr

    • electrons travel around the nucleus in shells in orbit

12. James Chadwick

    • neutron