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Proposed the idea that all matter is made from Air, Fire, Water and Earth. -
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Democritus believed that if matter was divided to smaller pieces there would be a point in which it could not be divided further. He said matter was made of indivisible (not dividible) particles called atoms -
While many advances were made in the area of chemistry during this time no significant advancement was made to the ideas of atoms and their makeup
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Isaac Newton theorized a mechanical universe with small, solid masses in motion. -
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John Dalton proposed that elements consisted of atoms that were identical and had the same mass and that compounds were atoms from different elements combined togethe -
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G.J. Stoney theorized that electricity was comprised of negative particles he called electrons. -
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Used experiments with Cathode Ray Tubes to determine the existance of the electron as well as the fact that electrons were negatively charged.
Later proposed one of the first atomic models known as the "Plum Pudding Model" -
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Rutherford did work in his lab to confirm Thomson's theory of the atom. His work however broke down the plum-pudding model.
The results of this experiment gave Rutherford the means to arrive at two conclusions: one, an atom was much more than just empty space and scattered electrons (J.J. Thomson model argued), and two, an atom must have a positively charged center that contains most of its mass (which Rutherford termed as the -
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Niels Bohr proposed an atomic structure theory that stated the outer orbit of an atom could hold more electrons than the inner orbit. -
There is no one scientist mentioned here because modern atomic theory is the collective work of many, many scientists! These include but are not limited to Max Planck, Albert Einstein, Werner Heisenberg, Erwin Schrodinger and others
In this model electrons are not located in discrete orbits, as hypothesized in the Bohr model, but instead occupy a hazier region, called an orbital. An orbital indicates a probable location of the electrons in an atom instead of a definite path.
