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Aug 25, 1000
Democritus's Theory.
(460-370 B.C.) Democritus was the first peron that suggested that matter could not be infinitely divided. He created the term "atomos" (atomas was later shortened to atom) to describe the particles that make up matter and move through empty space. "Atoms can not be created, destroyed, or further divided." -
Aug 25, 1001
Aristotle's Denial
(384-322 B.C.) Aristotle believed that atoms did not move through empty space and completely denied the existance of atoms due to personal ideas about nature. His ideas took Democritus's theory back to square one. -
Dalton's Theory
Dalton marks the beginning of the developement of modern atomic theory. He changed the word "atomas" to 'atom". He believed that atoms are the smallest particles of matter and are indivisible and indestructible. "Atoms can be rearranged, separated, or combined to form new things, but cannot be created, destroyed, or divided in the process." -
J.J. Thomson
J.J. Thomson designed a series of CRT experiments to determine the ratio of the particle's charge to its mass. He figured out that the mass of the particle is much less than that of the Hydrogen atom. Thomson discovered the electron, the first subatomic particle. -
Robert Millikan
Robert Millikan designed an oil drop apparatus to determine the change of the electron. He determined the magnitude of the charge of the electron and discovered the mass of the electron. -
Ernest Rutherford
Studied how positively charged a-particles interacted with solid matter. Calculated that an atom was mostly just empty space for electrons to move around in. Claimed that there had to be a place for the positive charge and the mass of an atom to reside. He says it was contained in the nucleus (a tiny region in the center of an atom). Rutherford called positively charged particles "protons". -
James Chadwick
Demonstrated that the nucleus had another neutral subatomic particle, the neutron. James Chadwick won the 1935 Nobel prize for his discovery of the neutron. -
The cathode Ray Tube
The cathode Ray Tube is a glass tube with the air removed from the inside chamberconnected to a cathode and an anode. This helped researchers study the relationship between mass and charge. While using a Cathode Ray Tube in a dark lab Sir William Crookes noticed a green flash of light. This small light gave way to the invention of the television.
