| A | B |
|---|
| John Dalton | Developed first atomic theory. Atoms of same element are the same and are not created or destroyed in chemical reactions |
| J.J. Thompson | identified the electron with cathode ray tube, "plum pudding model" |
| Ernest Rutherford | Gold foil experiment- discovered nucleus |
| Niels Bohr | Successive orbital shells of electrons like planets moving around the sun |
| Erwin Schrodinger | Developed Quantum mechanical model; viewed electrons as continuous clouds |
| James Chadwick | identified the neutron |
| Dimitri Mendeleev | first to organize the elements into a periodic table; arranged them by atomic mass |
| Henry Moseley | rearranged the periodic table according to atomic number- Father of Modern Periodic table |
| Democritus | 5th century Greek philosopher, Matter= indivisible particles |
| George Stoney | Proposed that electricity was made of particles called electrons |
| William Roentgen | Discovered X-rays in 1895 |
| Henri Becquerel | Discovered some chemicals spontaneously decompose and give off penetrating rays. Radioactivity |
| Marie Curie | 1898- Studied radioactivity in uranium and thorium. With her husband, she discovered radioactive poloium and radium |
| R.A. Millikan | Determined the charge and mass of an electron in the oil drop experiment |
| Louis de Broglie | Discovered that electrons had a dual nature, similar to particles and waves |
| Werner Heisenberg | Proposed Uncertainty Principle: you can't know both the position and velocity of a particle at the same time |
