sep 27, 1856 - JJ Thomson

Description:

Date: 1856 - 1940

Country: United Kingdom

Observations/Experiments/Evidence: To test the properties of the particles, Thomson placed two oppositely-charged electric plates around the cathode ray. The cathode ray was deflected away from the negatively-charged electric plate and towards the positively-charged plate. This indicated that the cathode ray was composed of negatively-charged particles.

Discoveries/Conclusions: In Thomson's model, the atom is composed of electrons surrounded by a soup of positive charge to balance the electrons' negative charges, like negatively charged “plums” surrounded by positively charged “pudding”

Contribution: Contributed to the development of the atomic theory which would shape our understanding of the world as a whole in the future.

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