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400
Democritus
"By convention bitter, by convention sweet, but reality atoms in a void" -
Atonnine Lavoisier
discovered the law of Conservation of mass, states that for any system closed to all transfers of matter and energy -
Dalton's Atomic Theory
all matter is made of atoms, atoms are invisible -
Dimitri Mendeleev
properties of elements “ were periodic functions of their atomic weights”, This became known as the Periodic Law -
J.J. Thomson
Used CRT to experimentally determine the charge to mass ration (e/m) of an electron, Studied “canal rays” and found they were associated with the proton H+ -
Plum Pudding Model
a model of the atom that incorporated the recently discovered electron -
Oil Drop Expirment
Oil drop experiment determined the charge and the mass of an electron -
Rutherford Model
relatively high central charge concentrated into a very small volume in comparison to the rest of the atom and with this central volume also containing the bulk of atomic mass. -
Electron Cloud Model
is an informal term in physics, it is used to describe were electons are when the go around the nucleus of an atom -
Ernest Rutherford
– Using alpha particles as atomic bullets, probed the atoms in a piece of thin gold foil. He established that the nucleus was: very dense,very small and posit -
Bohr Model
the model depicts the atoms as a small, positively charged nucleus by electrons that travel in circular orbits around the nucleus -
Gold Stringer Expirment
measured an alpha particle beam is scattered when it strike metal foil. -
Henry Moseley
Using x-rat tubes, determined the charges on the nuclei of most atoms, he wrote “The atomic number of an element is equal to the number of protons in the nucleus”. This work was used to reorganize the periodic table based upon atomic number instead of atomic mass -
Niels Bohr
Developed an explanation of atomic structure that underlies regularities of the of the periodic table. His atomic model had atoms built up of successive orbital shells of electrons -
James Chadwick
Using alpha particles discovered a neutral atomic particle with a mass close to a proton. Thus was discovered the neutron -
Cathrode Ray Tube
A vaccum tube containing one or more electron guns, and a fluorescent screen used to view images