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Democritus started to research the atom in 460 B.C, during the greek era. http://www.nobeliefs.com/atom.htm
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In 460 B.C. he dismissed the idea of the atom and people stopped researching for about 2000 years. http://www.nobeliefs.com/atom.htm
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In 1803 John Dalton performed experiments with various chemicals that showed that matter seemed to consist of bumpy particles. Although he did not know about their structure, he knew that the evidence pointed to something important. http://www.nobeliefs.com/atom.htm
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In 1898 the Curies were studying uranium and thorium and called their spontaneous decay process "radioactivity". She and her husband Pierre also discovered the radioactive elements polonium and radium. http://atomictimeline.net/index.php http://atomictimeline.net/index.php
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In 1900 Max Planck, a professor of theoretical physics in showed that when you vibrate atoms strong enough, you can measure the energy only in discrete units. He called these energy packets, quanta. http://www.nobeliefs.com/atom.htm
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In 1905, Albert Einstein wrote a ground-breaking about the "photoelectric effect." This is when many metals emit electons when light shines on them. http://www.nobeliefs.com/atom.htm
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Geiger created a machine that can count alpha and beta particles. Now this machine is quite simple it is very sensative. So sensative it can count a single partical. http://atomictimeline.net/index.php
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In 1909 Rober Millikan preformed an Oil drop experiment that determined the charge and the mass of an electron. http://atomictimeline.net/index.php
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Rutherford thought it would be interesting to bombard atoms with alpha rays, figuring that this experiment could look on the inside of the atom. He used Radium as the source of the alpha particles and shinned them onto the atoms in gold foil. Behind the foil sat a fluorescent screen for which he could observe the alpha particles impact. Now even tho the experiment results were not what what he thought they were going to be it made for a more accurate model of the atom. http://www.nobelief
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came up with the answer for atomic structure that underlies regularities of the periodic table of elements. His atomic model had atoms built up of sucessive orbital shells of electrons. http://atomictimeline.net/index.php
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In 1926 Erwin a famaous Ausrian physicist came up with an idea. Why not go all the way with particle waves and try to form a model of the atom on that basis? His theory worked kind of like harmonic theory for a violin string except that the vibrations traveled in circles. Pg. 99 of Modern Chemistry text book
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James Chadwick dicovered the neutron in 1932 by using alpha particles to discover a neurtral atomic particle with the similar mass of a proton. http://atomictimeline.net/index.php
