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400
Democritus
democritus found the atom. all atoms are indivisible. atom derives from atomos. atomos means indivisible in greek -
Period: 400 to
atomic theory
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John Dalton
he proposed atomic theory, with spherical solid masses in motion. atoms cant be made or destroyed -
wilhelm roentgen
while using a CRT, he observed neraby chemicals that glowed. some of the rays werent defelected by the magnetic field -
j. plucker
he built the first cathode ray tube -
jj thomson
he described atoms as balls of positive charge containing a number of elements -
aston
discoverd the existance of isotopes through the use of a mass spectograph -
bohr
he is the father of quantam theory. proposed the atom is successive or bital shells of electreons -
ernest rutherford
he developed the gold foil experiment rutherford determined that the nucleus of an atom is very dense and has a positive charge -
erwin shcrodinger
he proposed the electron cloud theory. schrodinger identified the electron cloud as the propable location of moving particles
