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5 Cards in this Set
- Front
- Back
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John dalton |
The billiard ball model: all matter is made up of particles could not be divided. He called these particles atoms billiard balls are like atoms you can't break it apart |
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William Crookes |
Plum pudding . Thomson said that atoms must have negatively charged particles called electronsWilliam Crookes invented the cathode ray tube . When he put electricity through the gas in the tube, it gave off a green light |
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Rutherford’s Gold Foil Experiment |
Ernest Rutherford was testing Thomson’s model of the atom. He shone very tiny, high speed particles (called alpha particles) through a piece of thin gold foil. He thought that the particles were so tiny that they would pass straight through the foil. Most of the particles did, but some were deflected. They must have hit something hard in the atom. |
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Bohr and Flame Tests |
Neils Bohr studied the element hydrogen. When he added energy, the atoms always gave off the same 4 colours of light. Each element has its own line spectrum (like a fingerprint)of light. Bohr realized that the light was given off when the electrons were given energy and got excited. When the electrons return to their non-excited state (ground state)they give off this energy as light |
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Chadwick and the Neutron |
A third particle in the atom was found, called the neutron. It is found in the nucleus and has no electrical charge, its neutral. This is the model of the atom that we still use today |
