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Name:____________________________________________________ Period:__________________ Review: Use the words below to fill in the blanks in the summary of atomic theories air Aristotle Atoms (2) cathode ray centrally cloud deflected Democritus diameter divisible earth electron electrons (2) fire indivisible mass negatively neutron nucleus positively protons (2) shape size water whole History has recorded many thoughtful leaders, their views and supportive research to unlock the keys of atomic structure. Greek philosopher _______________________ suggested that materials are made of small ______________________ units he called “atomos” leading to the modern name of _____________________. He proposed that these atoms were all composed of the same material and differed only by their _______________________________, _________________________ and ___________________________. During the same time period however, ________________________ disagreed with this proposal and countered by suggesting that all Earthly materials existed solely or in part as a result of ________________________, _________________________, _______________________, and _________________________. Fast forwarding to the 1700’s, John Dalton whose interest lay in weather prediction, conducted experiments with gases and found they could exert a pressure. He proposed the pressure resulted directly from the individual particles or __________________________ which he described as solid spheres making up the gas. He further found through mass studies that atoms combine with each other in _______________________________ number quantities. J.J. Thomson through studies with ___________________________________ tubes found that atoms were in fact ________________________ and discovered a ______________________ charged particle smaller than an atom, which we now call the __________________________. He proposed a model of the atom that described _____________________________ and ________________________________ scattered within a spherical shape structure. Ernest Rutherford, a student of Dalton, conducted an alpha particle experiment on gold foil having accepted Dalton’s explanation of atomic structure. Rutherford was surprised as alpha particles _________________________________ disproportionately more than expected as they passed through a thin sheet of gold atoms. As a result, Rutherford calculated the ______________________ of the gold nucleus. He also found the center of the atom to be ______________________ charged which suggested that protons must be ___________________ located rather than scattered around the atom. Today, we now know that the nucleus of all atoms is composed of both _____________________ and _______________________ and the electrons are found in the surrounding electron __________________________.