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400
The DIscovey of the Atom
In the Grreek era around 400 B.C. a man named Democritus discovered extremely small irreducible now known as the atoms. He said “Nothing exists except atoms and empty space. Everything else is opinion”. The atomic theory was rejected for a few malenias befoer people started belive it. -
Period: 400 to
The Atomic Atoms
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John Dalton
In 1803, John Dalton proposed an "atomic theory" with spherical solid atoms based upon measurable properties of mass. In his modle all atoms were the same in their chemical but in other elements they had different atomic weights. -
Sir William Crookes
In 1879 Sir William Crookes discovered that cathode rays fallowed straight lines from the cathode, cuases glass to flourse, imparts a neative charge to objects that it hits, also are deflected by electric feilds and magnets to suggest a negative charge. -
J.J. Thomson
He studied "canal rays" and found they were associated with the proton H +. Also he used a CRT to experimentally determine the charge to mass ratio (e/m) of an electron =1.759 x 10 8 coulombs/gram. -
Max Planck
Used the idea of quanta (discrete units of energy) to explain hot glowing matter. -
Albert Einstein
He published his famous equation E=mc 2. -
Glenn Seaborg
Form 1941-1951 Glenn Seaborg suggested to change the layout of the periodic table and he synthasized 6 transurainium elements.