Thomson Model
- Describe J. J. Thomson’s Plum Pudding Model and the experimental evidence that led him to propose it.
Cathode Ray Experiment
| Experimental Results | Explanation |
|---|---|
| Cathode rays are deflected by electric fields/magnets | Cathode rays are charged. |
| Cathode rays are deflected towards the positive plate | Cathode rays are negatively charged. |
| Obstruction in the path of cathode rays casts a shadow | Cathode rays travel in straight lines. |
| Green glow is seen opposite to the cathode | Cathode rays are emitted from the cathode. |
| Objects in the path of cathode rays experience force/increase temps | Cathode rays have mass |
| Z/M ratio is 1000 times greater than a hydrogen atom. | Cathode rays are made of particles that have much smaller mass than atoms. |
| Replacing the cathode with a different material doesn’t change the Z/M ratio | Cathode rays are made of particles that are all the same. |
Thomson’s Plum Pudding Model
The model has been since proven incorrect, but it stated that an atom consisted of a positively charged sphere with negatively charged electrons embedded in it. The electrons were thought to be like plums in a pudding, hence the name.
The sticky tape lab can be explained with Thomson’s model. The tape begins neutral, but when tape is pulled of the table, friction occurs that causes a loss of electrons on one tape to the other tape/table which causes the tapes to be charged.