-
460
Democritus
Democritus reasoned using philosphy that Atoms were indivisble and indestructable. His theory was the first stepping stone in a bath leading to the discovery of Atoms. -
Period: 460 to
Break in the timeline
Break in the timeline -
Period: 460 to
History of the Atom
-
Issac Newton
Newton theorized a mechanical universe with small, solid masses in motion. This meant that everything seen was not solid itself and not moving, but it was filled with many, many small solid masses in motion. He also theorized that atoms are held together by attraction. -
John Dalton
John Dalton was an english Chemist, and Meterologist. In 1803 expiriments with gasses first became possible in the world of Chemistry. This turn of the century event led Dalton to propose his modern take on the atom based on his own personal assumptions. These assumptions are known as the four point attomic theroy. -
Eugen Goldstein
Eugen Goldstein was a German pysisit, who is occasionally credited with discovery of the proton. Goldstein observed cathcode rays like Thomson did and noticed rays traveling in opposite directions to that of cathcode rays. This observation led to the discovery of the proton and its positive charge. -
JJ Thomson
Jj Thomson, and english physisist discovered the electron, along with its negative charge and the idea that electrongs have consistant charge to mass ratio. He discovered this by using a cathcode ray tube expiriment. He did this expiriment to find these things by observing the effects of the charges plated on the cathcode ray. -
Ernest Rutherford
Ernest Rutherford in 1899 studied absorbtion of gamma, beta, and alpha reys in thin sheets of metal foil. These types or expiriments were ones that Rutherford preformed all the time, so when he decided to do the gold foil expiriment, Rutherford found that atoms are mostly empty space and the mass of the atom is concetrated on the positvily charged nucleus containing protons, and neutrons. -
Robert Millikan
Robert Millikan was an American Physisist. In 1909 Millikan determined the size and charge of the Electron. He did this by preforming the oil-drop expiriment. When he did this he put a charge on a tiny drop of oil and measured how strong the applied electrical field had to be in order to stop the oil drop from falling. -
H.G.J Moseley
Henrey Gwen Jefferys Moseley used x-ray tubes to determinedthe 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
Bohr was a danish pysisit who expanded on Rutherford’s theory of empty space. His theory stated that electrons travel in orbits around the nucleus, and the outside orbits can hold more electrons than the inside orbits and these orbits determine the chemical properties of the atom. -
James Chadwick
James Chadwick was an English pysisist that discovered the neutron, With this disovery he found that the neutron does not have a positive, nor negative charge, and its mass is almost identical to that of a protons.
