| A | B |
|---|
| Avogadro | Stated that equal volumes of gases, under the same conditions, have the same number of molecules |
| Becquerel | Found that Uranium exposes photographic plates |
| Bohr | Worked with Rutherford to come up with a planetary model for the atom |
| Chadwick | Identified neutrons |
| Dalton | Proposed a five point theory of atoms to explain many of the properties of many chemicals and compounds |
| Democritus | Greek Philosopher who suggested that the world was made of empty space and "atoms" |
| Einstein | theorized that energy is equal to mass times the speed of light squared |
| Gay-Lussac | Noted that, under constant conditions, the volumes of reacting gases and gaseous products are in the ratio of small whole numbers |
| Geiger and Marsden | worked for Rutherford and found that most of the atom is empty space |
| Lavoisier | First proposed that in ordinary chemical reactions, matter can be changed in many ways, but it cannot be created or destroyed - Law of Conservation of Mass |
| Mendeleev | Organized elements according to properties and atomic mass to create the Periodic Table |
| Millikan | Used oil drop experiment to obtain the first accurate measurement of an electron's charge |
| Moseley | Was able to determine atomic numbers for atoms causing the Periodic Table to be revised |
| Planck | Assumed that energy, instead of geing given off continuously, is given off in little packets, or quanta |
| Proust | Observed that specific substances always contain elements in the same ratio by mass - Law of Definite Proportions |
| Rutherford | Discovered that the atom contains a positive nucleus using the gold foil experiment |
| Thomson | Discovered that cathode rays consist of electrons and observed that atoms can have isotopes |
| M. & P. Curie | found that rays are given off by radium and uranium |
| Dobereiner | Found that some elements had similar properties |
| Newlands | Tried to arrange elements according to atomic mass |
