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400
Democritus (400)
He said that he knew they existed but never existed saw them. He found this out through his theory based on observations and natural curiosity.
What Democritus Thought. Democritus Model.Lenda Benett,2012 -
Dalton (1803)
He said that:
-Atoms are not destroyed during chemical reactions they are arranged different.
-All matter is made up of atoms.
-All atoms of a element are the same
His model was dubbed " Billard Balls"
He figured it out by using some chemical reactions ad saw how one substance changed into another.
Bennett, Linda. "What Dalton Discovered." Dalton's Model. N.p., 2012. Web. 24 Feb. 2015. -
J.J. Thompson (1897)
He said that the electrical charges have a negative charge! So that means electrons have a negative charge.
He found this out by using cathode rays. Electrons went away from the negative pole and attracted to the positive pole.
Bennett, Linda. "What Thompson Discovered." Thompson's Model. N.p., 2012. Web. 23 Feb. 2015. -
Rutherford (1911)
Leon, De. "Rutherford Model of the Atom." Rutherford Model of the Atom. C101 Class Notes, 2012. Web. 23 Feb. 2015.He said that all the positive charge was in the center of the atom. He changed it by adding the nucleus to the model of the atom.
The method he used involved gold foil and a shot of alpha particles. All the atoms bounced back and none of them had gone through like most people had thought. He called his model the planetary model. -
Bohr (1922)
["Rutherford and Bohr Describe Atomic Structure 1913." PBS. PBS, 1998. Web. 24 Feb. 2015.](Rutherford and Bohr describe atomic structure1913)He thought how in a solar system planets are pulled together by gravity. Well the same thing happens with atom but instead electricity pulls everything together. He used mostly math to make this discovery. He said his model looked like a solar system.
