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Period: 460 to 550
The Idea of the Atom
It was created by two Greek "thinkers" Leucippus and Democritus, they refused to believe that everything is one thing; nothing smaller. They called these small particles "atomos". -
Oct 12, 640
Aristotle's opinion
Aristotle apposed the idea of everything is made from small things. He believed that no matter how many times you cut something in half it's the same. Aristotle believed in the four elements air, earth, water and fire. His theory went on for so long because he taught Alexander the Great. -
John Dalton
He proposed the Law of Multiple Proportions. This law led directly to the proposal of the Atomic Theory in 1803. He also proposed a system of symbols to represent atoms of different element. Dalton noticed the existence of atoms of elements and that compounds formed from the union of these atoms. -
Dimitri Mendeleev
he created the periodic law and the periodic table in 1869, he ordered them to increase in atomic weight( number of protons) and left holes for undiscovered elements. -
J.J. Thomas
He discovered the electron in a cathode ray tube in 1897, he conclude that the electron was a component of all matter. Then he created a model known as the"plum pudding" model. the protons which act as the pudding and the electrons that act as the raisins. -
Robert Millikan
He determined the unit charge of the electron in 1909 with his oil drop experiment at the University of Chicago. Thus allowing for the calculation of the mass of the electron and the positively charged atoms. -
Ernest Rutherford
Rutherford created a model known as the "gold foil" model. In this model he discovered that atoms contain a nucleus. In the experiment he shoots alpha particles at a thin sheet of gold foil to see if it would it something and bounce off. Most of the particles went right through and some hit changinging its direction. Some of the particles even bounced back to where they were launched. -
Rutherford's Experiment
in 1920 he proposed the existence of a third particle known as the neutron from his study on his last model. -
AntiMatter Trapped for 16 Minutes
Scientist created antimatter and kept it stable for 17 minutes even afterwards it didn't explode. Scientist cannot study antimatter because they can't keep it long enough. Although not alot is clear on antimatter this is still the longest time its been trapped. A Canadian team of scientist only trapped the anti atom for 1,000 seconds. -
James Chadwick
He was a collaborator of Rutherford's, in 1932 he discovered the neutron. His researched led to fission and ended with the atomic bomb.
