| Term | Definition |
| Charles Darwin | theories of biological evolution |
| John Dalton | English Quaker' formulator of the atomic theory |
| Dimitri Mendeleev | Russian chemist; organized the periodic table |
| William Roentgen | German physicist, X-ray tube |
| Henry Moseley | British scientist; used x-ray tube to observe atoms |
| Pierre and Marie Curie | French/Polish scientists; discovered new elments in uranium ore |
| Ernist Rutherford | British physicist; parts of atoms |
| Niels Bohr | Danish physicist; parts of a nucleus |
| Albert Einstein | German Mathematician; relationship of matter and energy (E=mc^2); theory of relativity |