| A | B |
|---|
| Democritus | Coined the water atom from the Greek word, atomis |
| John Dalton | Proposed the first "atomic theory" |
| Dmitri Mendeleev | The Father of the periodic table and discovered the periodic law |
| Sir William Crookes | Discovered various properties of cathode ray tubes |
| Wilhelm Roentgen | discovered x-rays |
| Henri Becquerel | discovered radioactivity |
| JJThompson | used the cathode ray tube to discover the electron and proposed the plum pudding model of the atom. |
| Ernest Rutherford | Used alpha radiation and a thin piece of gold foil to discover that atoms have a very dense central nucleus that is positive |
| Mosely | define the atomic number of an element |
| Niels Bohr | Developed an atomic model of thea atom where electrons circle the nucleus in specific shells |
| James Chadwick | Discovered the Neutron |
| Enrico Fermi | Conducted the first controlled nuclear chain reaction |
| Marie and Pierre Curie | Discovered Radium and Polonium |
| Robert Oppenheimer | Lead a team of scientists involved with the Manhatten Project |
| Robert Millikan | Determine the charge of the electron |
