Discovery of Electrons and Protons

This power point slides presents how the electrons and protons were discovered together with the personalities involved with this scientific breakthrough.

1. Discovery of Electrons and Protons

2. Notable Scientist Sir William Crookes (1832-1919) British Chemist and Physicist British National Worked on vacuum and Crookes tube and led advancement in the discovery of electrons

3. Notable Scientist Sir Joseph John “J.J” Thomson ( 1856-1940) English Physicist British National Credited for: Discovery of Electrons Nobel Prize in Physics (1906)

4. Discovery of Electrons Cathode Ray Tube

5. Important Observations: The beam were easily bent when passing through a parallel plate Bent towards the Positive Charge( +) Bent away from the Negative (-)

6. Key Concepts: Since the beam was bent so easily: Made up of a very light particles lighter than a H atom He thought that there are even smaller particles inside an atom.

7. Key Concepts: Since the beam bent towards the positive charged plate : Since like charges repel and unlike charges Attract Beam carried a negatively charge particle He called them “ELECTRONS”

8. Notable Scientist Eugen Goldstein (1850-1930) German Physicist German Nationa l Discovered: Anode Rays Sometimes co-credited on the discovery of protons

9. Important Observations:

10. Notable Scientist Ernest Rutherford (1871-1937) British Physicist New Zealander National Nobel Prize in Chemistry (1908) Discovered the Protons Gold Foil Experiment

11. Gold Foil Experiment

12. Important Observations: Alpha Particles ( α ) from Uranium were shot directly to the gold foil Almost all of the α particles passed through Some α particle bent off-course at some degree Least amount of α particle bounced back from where it came.

13. Key Concepts: Since the Nucleus was very small most α particle completely missed them . If some α particles comes close its positive charge causes repulsion and bend them off course .

14. Gold atoms were mostly empty-space There must be something inside hard and heavy

15. Key Concepts: If the α particles makes a direct hit it would bounce back Since the nucleus is much heavier than the α particles

16. Discovery of Protons The particle that was inside the small lumps that causes repulsion of α particles were positively charge. Then lately he discovered the particle that causes the positive charge and called them “ PROTONS ”