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460 BCE
Democritus
Democritus was the first scientist to create a model of the atom. He was the first one to discover that all matter is made up of invisible particles called atoms. He created the name "atom" from the Greek word "atomos", which means uncuttable. He also discovered that atoms are solid, insdestructable, and unique. HIs model was just a round solid ball. Democritus didn't know about a nucleus or electrons, all he knew was that everything is made of atoms. -
460 BCE
Democritus DOB
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400 BCE
Democritus's Discovery of the Atom
He called it the basic building block of life -
359 BCE
Democritus DOD
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398
400 BCE world event
Xenophon's successful march through the Persian Empire encourages Sparta to turn on the Persians and begin wars against the Persians in Asia Minor. -
John Dalton
John Dalton was an English chemist, physicist, and meteorologist who is best known for introducing the atomic theory into chemistry. His atomic theory includes the following statements: Matter is made up of small particles called atoms. Atoms are indivisible and cannot be created or destroyed. All atoms of a given element are identical and have the same weight. Atoms of different elements have different weights. -
John Dalton's Marble Model
He defined an atom to be a ball-like structure, as the concepts of atomic nucleus and electrons were unknown at the time. -
John Dalton DOB
Was born on September 6th, 1766 -
Michael Faraday
Michael Faraday was a British scientist who contributed to the study of electromagnetism and electrochemistry. His discoveries include: Magneto-electric induction The motion of a magnet inside a wire coil could produce electricity. Faraday effect The relationship between magnetism and light. Electromagnetic induction The process of creating a flow of electrons through the use of wire and magnets. -
Michael Faraday DOB
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World Event in 1803
The Louisiana Purchase is made from France by the United States. -
John Dalton DOD
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Eugen Goldstein DOB
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Eugen Goldstein
Eugen Goldstein was a German physicist. He was an early investigator of discharge tubes, the discoverer of anode rays or canal rays, later identified as positive ions in the gas phase including the hydrogen ion. He was the great uncle of the violinists Mikhail Goldstein and Boris Goldstein. Wikipedia -
JJ Thomson DOB
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Robert Millikan DOB
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Michael Faraday DOD
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Ernest Rutherford DOB
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Niels Bohr DOB
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Erwin Schrödinger DOB
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James Chadwick DOB
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J.J Thomson
J.J. Thomson was a very important scientist when it came to the atomic model. Up until his time, all models of the atom looked like a big solild ball. J.J. Thomson discovered the electron, which led him to create the "plum pudding" atomic model. In this model, he thought that the atom was mostly positive, and negative electrons wandered around the atom. The "plum pudding" model influenced other scientists to make better atomic models. -
Werner Heisenberg DOB
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Neils Bohr
Niels Bohr was a Danish scientist that was a student of Rutherford. He decided to make a new model based off of Rutherford's model, but changed the orbit of the electron. Also, he created energy levels in the atom, where only a certain amount of electrons could fit on one energy level of the atom. Bohr also used Planck's ideas in order to create quantum mechanics, his new concept regarding energy. This model is still used to this day. -
World Event in 1902
Philippine–American War ends -
Neils Bohr Solar System Model
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World event in 1904
October 21 – Russo-Japanese War: Dogger Bank incident -
Plum Pudding Model
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Robert Millikan
Robert Millikan was an American scientist that was very interested in J.J. Thomson's finding of the electron. J.J. Thomson predicted that the electron was 1000 time smaller than the atom. Millikan wanted to prove this hypothesis. He preformed an "oil-drop experiment" in which he found that J.J. Thomson was correct. Millikan was also involved in the Quantum Theory after he was inspired by Max Planck. Millikan inspired other scientists to explore parts of the atom. -
Ernest Rutherford
Ernest Rutherford was another scientist that changed the atomic model. He felt that J.J. Thomson's model was incorrect, so he created a new one. He created the nucleus, and said that instead of the positive matter being the whole atom, it was just in the middle. He said the atom was mostly empty space and that the electrons surrounded the positive nucleus. This model influenced one of his own students to perfect the atomic model later on. -
Ernest Rutherford's Nuclear Model
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Erwin Schrödinger
Erwin Scrhodinger was an Austrian scientist that worked with the Quantum model of the atom. He disagreed with Bohr's theory, so he created his own. He thought that the only way to find the location and energy of an electron in an atom was to calculate its probability of being a certain distance from the nucleus. This equation influenced the Quantum mechanical model of the atom. -
World Event in 1926
The 1926 Imperial Conference opens in London. -
Erwin Schrödinger Electron Cloud Model
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Werner Heisenberg
Werner Heisenberg was a German scientist that proposed the uncertainties of the Quantum model. He said that you can't know the exact velocity and momentum of the electron at the same time, which means you can't know the exact location of the electron. This principle proves error in Bohr's model because of the uncertainty of the location of an electron. -
World Event 1932
Japan declares Manchukuo (Japanese name for Manchuria) formally independent from China -
James Chadwick
Jame Chadwick was an English scientist that discovered the neutron. Before this discovery, Rutherford had concluded that the nucleus was made of positive matter. It made sense that the atom was neutral because the negative electrons and the positive protons cancelled out. But, Chadwick started to question why there was a difference between the atomic mass and the number of protons. Chadwick then found that the missing component was a neutral part: the neutron. -
James Chadwick Electron Cloud Model With Neutrons Added
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Ernest Rutherford's DOD
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JJ Thomson's DOD
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Robert Millikan DOD
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Erwin Schrödinger DOD
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Niels Bohr DOD
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James Chadwick DOD
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Werner Heisenberg DOD