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J.J. Thompson's Model of the Atom
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J.J. Thomson's Model of the Atom
Billiard Ball Model
Who created it?
What is it?
John Dalton, an English chemist, physicist, and meteorologist, created the Billiard Ball model in 1801.
His theory consists of four statements:
1. Atoms are tiny, invisible particles.
2. Atoms of one element are all the same.
3. Atoms of different elements are different.
4. Compounds form by combining atoms.
The Billiard Ball
The Plum Pudding Model
Description:
Why Dalton was wrong
Thomson proposed a plum pudding model, with positive and negative charge filling a sphere only one ten billionth of a meter across. It has negatively charge particles (known as electrons today, Thomson called them 'Corpuscles') surrounded by positively charged particles. Thomson suggested that it made up all of the matter in atoms.
The indivisibility of an atom was proved wrong: an atom can be further subdivided into protons, neutrons and electrons. However an atom is the smallest particle that takes part in chemical reactions.
New Evidence
J. J. Thomson discovered the electron with his experiment in 1856-1940. He found this out in his experiment design: the high-vacuum cathode-ray tube.This helped him develop the plum pudding model.
Experimental Design
Electric discharge in a high- vacuum cathode- ray tube
At the Cavendish Laboratory at Cambridge University, Thomson (1856–1940) discovered the electron in a series of experiments designed to study the nature of electric discharge in a high-vacuum cathode-ray tube.Thomson interpreted the deflection of the rays by electrically charged plates and magnets as evidence of “bodies much smaller than atoms” that he calculated as having a very large value for the charge-to-mass ratio.
By: Kaysee, Brandon, & Elissa