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450
Democritus (430 B.C.)
"Google Image Result for." Google Image Result for. N.p., n.d. Web. 24 Feb. 2014.Democritus proposed that all matter is made up of particles called atoms.To make this discovery, he would sit and watch decay and mix elements together. His model of the atom was just a round sphere (ball). -
450
Aristotle (350 B.C.)
Aristotle denied the theory of atoms. He believed that everything was made of the four elements water, wind, fire, and earth. He did not have a model of the atom. -
Period: 450 to
History of the Atom
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Dalton
Dalton proposed the Atomic Theory. Which states that all matter is made up of particles that cannot be taken apart, called atoms. He also said that all atoms have unique properties, either simple(element), compound, or complex. To discover this he did experiments with different chemicals and discovered that matter consists of "lumpy particles(atoms)". He did not know about their structure, but he knew evidence showed something fundamental. -
Thomson
T.J. Thomson discovred electrons. He believed the atoms had large boundries of positive charge with negative parts stuck within it. He called it the "PlumPudding" model. -
Rutherford
He discovered there was a large nucleus with an overall positive charge. Rutherford shot alpha particles at gold foil. The path curved indicating there was something there with a large positive charge. His model, called "Rutherford's Atom" , showed the electrons orbiting a positive center, like the sun and planets. -
Heisenberg and Schrodinger
Erwin Schrodinger showed that electrons are really waves. The "two split experiment" showed electrons travel in waves if the high point on the waves meet, so do the bottom points. He believed when the atom was unstable the electron wave was curvy and unbalanced but when it is stable the wave goes in a slow wave pattern.
