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200
382 BC-Aristotle
Aristotle is a greek philosopher that disagreed with Democritus's ideas. He beleived that you can never end up with a particle that can not be cut. -
250
440 BC- Democrjtus
Denocritus thought that you would evebtually end up with a particle that could not be cut. He called it an atommeaning "not able to be divided". He also though particles were small and hard -
John Dalton
John experimented with different substance during his work. He wanted to know why certain proportions based on mass to form compounds. His theory was that substances are made of atom, atoms of the same element are exactly alike, and that atoms joined with other aatoms to make a new substance. -
Thomson
Thomson discovered that there are small particles inside the atom. He also discovered that a positively charged plate is attracteds the beam. He concluded that the beam was negativly charged. -
Schrodinger and Heisenberg
Schrodinger and Heisenberg explained the nature of electrons in an atom. The discovered that the electrons have no path. Also they found that there is a place were electrons can be found which is called the electron cloud. -
Rutherford 1909
Rutherford tested Thomsons theory in 1909. He dicoverd that most of the particles went through the gold but a few bounced.He conclued that atoms must be mostly empty space with a small part made of highly dense matter. -
Rutherford1911
Rutherford said that in the atom the tiny center is extremely dense and positivly charged. He called this the nucleus.During his research he discovered that the diameter of the nucleus was 100,000 times smaller then the diameter of a gold atom. -
Bohr
Borhs theory is that the electrons have a path. In his studys it was proven that they just jump from atom to atom. -
Period: to
The Development of the Atomic Theory
