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(Democritus about 460 BCE-370 BCE) Democritus gives atoms their name: “Atomos,” which means “indivisible”. He comes up with the general idea that atoms make up the world. He believed them to be indestructible hard objects arranged uniformly.
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Sophocles’ famous drama is first performed in Athens.
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(Dalton Sept 6, 1766 - Jul 27, 1844) Dalton makes several conclusions about atoms. He finds that atoms are the smallest form of mass and cannot be broken down into smaller pieces. He also determines elements are distinguished by the mass of their atoms, and one element is made of identical atoms with the same size and shape. He also figures that atoms combine to create molecules, which he visualizes through the usage of wooden balls and sticks. -
(Faraday Sept 22, 1791 - Aug 25, 1867) Faraday discovers that running an electrical current through water causes the molecules to dissociate.
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(Goldstein Sept. 5, 1850 - Dec. 25, 1930) Goldstein figures out that charged ions move from negative to positive.
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(Thompson Dec 18, 1856- Aug 30, 1940) JJ Thomson discovers the existence of the electron
In Thomson’s model of an atom, the electrons are suspended in positive matter like plums suspended in the pudding. -
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(Rutherford Aug 30, 1871- Oct 19, 1937) Rutherford now believes that the nucleus is the atom's core. -
(Millikan Mar 22, 1868 - Dec 19, 1953) Through his “Oil Drop” experimentation, Millikan successfully proves the existence of the electron and successfully determines that it had a negative charge.
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He also figured that electrons orbit the nucleus while the rest is empty space. -
(Neils Bohr Oct 7th, 1885 - Nov 18, 1962) Bohr discovers that electrons orbit the nucleus at a constant distance, which is different from previous ideas that the electrons were following no track. -
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(Chadwick Oct 20, 1891 - Jul 24, 1974) Chadwick completes the atom with his discovery of neutrons in the nucleus -
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(Schroedinger Aug 12, 1887 - Jan 4, 1961) Schroedinger correctly formulates an equation to calculate the energy level of electrons within atoms. He also determines that rather than being on a set track around the nucleus, electrons follow a general path. -
(Heisenberg Dec 5, 1901 - Feb 1, 1976) Heisenberg comes up with the uncertainty principle, which asserts that no particle’s position or momentum could ever be exactly determined.
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