click below
click below
Normal Size Small Size show me how
History of the Atom
| Question | Answer |
|---|---|
| John Dalton | Believed atoms were fundamental particles. (nothing smaller than them) Indivisible. Can't be created or destroyed. |
| Law of Conservation of Mass. | Matter is neither created or destroyed in the course of a chemical reaction. |
| Crookes | Cathode rays. (negative plate) Discharge tube, low pressure. Electricity passed through the tube, producing invisible rays travelling in straight lines from the cathode to the anode. |
| Cathode rays are.. | ..streams of negatively charged particles called electrons. |
| JJ. Thomson | Electron. Neg. and pos. plates. Cathode rays. Beam struck a fluorecent screen. Plum pudding model. |
| Milikan | Determined the charge and mass of an electron using charged oil droplets. |
| Plum pudding model. | Pictured the atom as a sphere, which is positively charged and has the negatively charged electrons embedded in it. |
| Rutherford | Gold foil and alpha particle experiment. Discovered the nucleus. Discovered protons..alpha particles ejected positive particles from oxygen and nitrogen atoms. |
| Chadwick | Discovered neutrons..alpha particles ejected neutral particles from beryllium. |