1. PARTS OF THE ATOM
electrons
protons
neutrons

2. J.J. THOMSON ( )

3. J.J. THOMSON ( )
1897 – discovered electrons: negatively charged subatomic particles
experimented using flow of electric current through gases

4. CATHODE RAY TUBE

5. CATHODE RAY TUBE More proof:
added + and – charged plates: cathode ray is attracted to + plate

6. CATHODE RAY TUBE

7. CATHODE RAY TUBE More proof:
added + and – charged plates: cathode ray is attracted to + plate
used different gases – always saw beam; different intensities
used different metals – always saw beam; different intensities

8. CONCLUSIONS
cathode rays - must be negatively-charged particles: ELECTRONS!
these particles are part of every atom
calculated mass of e- = 1/2000 of the mass of a hydrogen atom

9. CROOKES TUBE proved that electrons have mass
no fluorescent screen in cathode ray tube
Crookes tube video