Saint's Log

Chemistry Basics II

Chemistry Basics I covered the sections on scientific discovery up to atomic theory. Next is the question of what atoms are made of. Enter JJ Thomson with his CRT experiments. These 3 videos explain his discovery of the electron. I watched multiple just to see different perspectives on the same experiment.

It was after watching the next one that I found myself wondering how you pump all the air out of a glass bottle.

After it had been established that electrons exist and that they have negative charge, it naturally follows that we would want to know what the charge on an electron actually is. This was resolved by Millikan’s oil drop experiment.

This next video on the oil drop experiment was helpful because it showed a similar but modern setup.

The discovery of electrons, combined with the fact that matter is in general electrically neutron implies that there must be positively charged particles. Ernest Rutherford’s gold foil experiment confirms this:

At this point I have several questions that will have to wait for another time.

1. How are magnets made (e.g. the ones used by J.J. Thomson)?
2. How were alpha particles Rutherford was using discovered?
3. How was it shown that the electrons move around the nucleus?
4. How were neutrons discovered?
5. How was the mass of a proton established?