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Democritus discovered the atom
Democritus took a seashell and broke it in half. Then he kept breaking the parts of the shell into halfs until there was only a powder left. He called this thin power atoms. Democritus said that the "atoms" combined together to make a object. -
John Dalton discovery of Matter.
John Dalton's discovery of matter went along with Democritus' discovery of the atom. John Dalton proved that the atom discovery was correct. Dalton discovered that all matter is made up of atoms and that atoms are indivisible and indestructible. He also found out that all atoms of a given element are identical in mass and properties. -
J.J. Thomson discovered the electron.
J.J. Thomson discovered the electron during one of his studies in his lab. A glow could be observed when a high voltage was applied to a test tube. He thought that the glow came from something inside the tubes. Thomson made many experiments to study the properties of the rays coming from the tubes. He then determined the ratio between eletric charge and mass. With the results he discovered the atom. Later he created the Plum Pudding Model which says that atoms contain fewer electrons. -
Robert Milliken discovered how to meausure the charge of an electron.
Robert Milliken discovered how to measure the charge of an electron by using the Oil Drop Experiment. In the experiment he took charged droplets of oil between 2 horizontal metal electrodes. With the charged droplets of oil he measured how strong an applied electric field had to be in order to stop the oil drop from falling. -
Ernest Rutherford discovered the nucleus and proton
Ernest Rutherford discovered the nucleus by using the Gold Foil Experiment. The Gold Foil Experiment would be used to see if any paricles would go through a very thin foil which was made out of gold. He explained later by saying it was like you fired 15 shell at a tissue. He later discovered that the nucleus had a particle that had a positive charge which he later name the proton. -
Niels Bohr created the Bohr Model.
Niels Bohr created the Bohr Model. The Bohr Model shows the atom as a small and positively charged nucleus surrounded by orbiting electrons. He was also the first person to discover that electrons orbit in seperate orbits and that the number of electrons in the outer orbit determines the property of an element. -
James Chadwick discoverd the neutron.
James Chadwick discovered the neutron by using scattering data to calculate the mass of the neutral particle. He took Rutherfords proposal that there might also be a neutral particle in the nucleus. Chadwick proved the Rutherford was correct by doing experiments. Chadwich did experiments that Frederic and Irene Joliot-Curie used to try track radiation. Chadwick was looking for something similar to the proton but with zero charge. He became successful with his experiments and found the neutron.
