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5 Cards in this Set
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- Back
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What did JJ. Thomspon discover and when? |
In 1897 JJ.Thompson discovered that atoms werent solid spheres. His measurements of mass and charge show that an atom must have negitavley charged particles- an electron. From these results he made the plum pudding model where the plum is the negative electrons surrounded by the pudding which is the positive charge. |
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what was the gold foil experiment? |
In 1909 Ernest Rutherfood who worked with Geiger and Mardsen did the " gold foil experiment" where they shot positivley charged alpha partices at a thin gold sheet. From this experiment they expected the alpha particles to go straight through but instead some of them deflected in the oppostie direction. something that the plum pudding model could not explain. Rutherfod then came up with a new theory. |
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What was Rutherfords theory? |
Rutherford came up with the nuclear atom theory where most of the mass was in the positavley charged nucelus surrounded by a " cloud" of negitavley charged electrons and the rest of the atom is empty space. |
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Why did Rutherfords theory fail? |
Scientists discovered that the "cloud" of electrons would be attracted to the nucleus which would cause the atom to collapse. |
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what was Neil Bohrs theory? |
He came up with the idea that electrons were in fixed shells and they have fixed energy. They can only move around in their shell and not in between. |
