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Democritus was the first to say that all materials were made up of uniform, solid, indestructible, structures called atoms. He also theorized that they moved in infinite numbers through empty space. -
The Battle at the Allia River between Rome and the Gauls. This resulted in a Gallic victory and the sack and burn of Rome. -
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John Dalton theorized that atoms could neither be created nor destroyed. He also was the first to theorize that all atoms of a certain element had identical size and mass while differing elements had different atoms. -
During the war of 1812, in 1814 the British burnt down the white house along with many other federal buildings. -
He was the first to realize that atoms were somehow related electromagnetically. Although he did not know exactly how they were. -
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He discovered that inside an atom, there was evidence of positively charged particles. -
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JJ Thomson discovers negatively charged particles in the atom. -
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Wilbur and Orville Wright make the first functional powered airplane called the Wright Flyer. -
Using his discovery of the electron and the idea of positively charged matter in the atom he proposed his own idea of what an atom looked like. He claimed that there were negatively charged electrons within a collection of positively charged matter. -
Robert Millikan researched electrons and discovered the exact magnitude of the electron's charge. He also discovered that every electron has the same amount of negative charge. -
Rutherford made a model of what he thought the atom looked like. He proposed that the positively charged matter discovered earlier was in the middle with the electrons on the outside. -
Bohr made a new model of the atom that proposed that the electrons have discrete energy levels and that the electrons have a stable orbit around the nucleus of the atom. -
Ernest Rutherford discovered that the positively charged matter discovered earlier was a particle called a proton. -
Federal law passed banning alcohol and beginning prohibition in the United States. -
He applied a wave equation that he formulated to correctly calculate the chance that an electron was in an area surrounding the nucleus. he used this discovery to make a model with Werner Heisenberg that consisted of a dense cloud of nucleus surrounded by a dense cloud of electrons. -
Werner Heisenberg uses theories in quantum mechanics to make the “electron cloud” model of the atom with Erwin Schrodinger. -
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He discovered the neutron, which was a neutral-charged particle in the nucleus of an atom along with the positively charged proton. He then used this discovery to create his model of the electron cloud model using the neutron. -
All features of the Hoover Dam were completed. It immediately became the tallest dam in the world. -
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World War II begins with the German invasion of Poland. -
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