1. By: Ashley Morgan Periods: 3 rd & 4 th By: Ashley Morgan Periods: 3 rd & 4 th Atomic Theory Timeline

2.  Atoms are the fundamental building blocks of matter. The Atomic Theory

3. 442 B.C. Democritus  Democritus stated that all matter is made up of atoms. He also stated that they are so small that they can’t be divided, and they entirely fill up the space they’re in.

4. 384-322 B.C. Aristotle  Aristotle provided the method of gathering scientific facts, which proved as the basis for all scientific work.

5. 1777 Antoine Lavoisier  Lavoisier is the founder of modern chemistry. He showed that chemical elements were neither created nor destroyed, just combined into different compounds in chemical reactions. In other words, he distinguished between an element and a compound.

6. 1799 Joseph Louis Proust  Proust is known for the Law of Definite proportions. This states that a chemical compound always contains exactly the same proportion of elements by mass.

7. 1803 John Dalton  John Dalton formed the atomic theory, which states that all matter is composed of tiny, indestructible particles called atoms. They are all alike and have the same atomic weight.

8. 1832 Michael Faraday  Faraday developed the Laws of Electrolysis. This is the splitting of molecules with electricity.

9. 1896 Henri Becquerel  Becquerel is noted for the discovery of Radioactivity.

10. 1898 Marie & Pierre Curie  The Curies stated that radioactive materials cause atoms to break down spontaneously, releasing radiation in the form of energy and subatomic particles.

11. 1898 J.J Thomson  Thomson discovered the electron and developed the plum-pudding model of the atom.

12. 1900 Max Planck  Planck stated that energy is radiated in small units, which he called quanta.

13. 1905 Albert Einstein  Einstein stated light was made up of different particles, that, in addition to wavelike behavior, demonstrate certain properties unique to particles.

14. 1908 Robert Milikan  Millikan was able to find out the electric charge of the electron.

15. 1909 Ernest Rutherford  Rutherford used the results of his gold-foil experiment to state that all the mass of an atom were in a small positively-charged ball at the center of the atom.

16. 1913 Neils Bohr  Bohr stated that the electrons moved around the nucleus in successively large orbits.

17. 1931 James Chadwick  Chadwick is noted for the discovery of the neutrally- charged neutron.