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Jan 1, 1000
Romans theorize atoms
They think there is something that cant be cut in half. Name after word that means uncuttable. -
Period: Jan 1, 1000 to
Nothing notible
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John Dalton Says four things about atoms
(1) Matter is made up of atoms
(2) Atoms cannot be devided into smaller peices
(3) All atoms of an element are exactly alike
(4) Different elements are made up of different kinds of atoms -
William Crookes makes CRT
William Crookes makes the cathrode-ray tube by taking most of the air out of a glass, attaching metal plates to either side, and attaching a battery. Green glow goes from negative side to positive. Discovers protons -
JJ Thomson proves Crookes
He uses a magnet on the CRT and the ray bends showint that the particles are electrically charged instead of just being light. Creates a model with electrons surrounding a proton. -
Ernest Rutherford tests Thomphons model
Scientist Ernest Rutherford sets up an experiment. He takes a peice of gold less than the width of paper and shoots positively charged particles at it. he expects for the particles to go right through the gold and hit the other side in a straight line. instead some bounce off. comes up with a more modern model with a neuclus with electrons circling it. -
Period: to
More Changes
Physicists start to think that electrons dont move in a perfect orbit. Eventually make the electron cloud model where there is plenty of space for electons to move.