Name: ______________________________________ Date: __________________ Period: ________ Page: _______ The History of the Atom What is an atom? _______________________________________________________________________________ Directions: As you watch the video, draw the models of the atom (except for Aristotle) and highlight key points. History of Atomic Structure Timeline Scientist’s Picture of Date Model of the Atom Scientist’s Contributions Name Scientist Democritus Was the first to discuss the Atomic Theory All things were made of tiny, invisible, indestructible BC particles, called atoms Thought atoms varied in size, shape and weight Aristotle Opposed the Atomic Theory Thought matter was made of air, water, fire, and Earth BC 1808 John Dalton Atomic Theory All matter is made up of atoms All atoms of a given element are identical in mass and properties Compounds are formed by a combination of 2+ different kinds of atoms A chemical reaction is the rearrangement of atoms X Atoms are indivisible and indestructible 1897 J.J. Cathode Ray Experiments Thomson Discovered the Electron Negatively charged subatomic particle Plum Pudding Model The electrons are distributed throughout the atom with their charge balanced by the presence of a uniform sea of positive charge 1911 Ernest Gold Foil Experiment Rutherford Observation: Some alpha particles deflected to the side and back to their origin
Name: ______________________________________ Date: __________________ Period: ________ Page: _______ The History of the Atom What is an atom? _______________________________________________________________________________ Directions: As you watch the video, draw the models of the atom (except for Aristotle) and highlight key points. History of Atomic Structure Timeline Date Scientist’s Name Picture of Scientist Model of the Atom Scientist’s Contributions BC Democritus Was the first to discuss the Atomic Theory All things were made of tiny, invisible, indestructible particles, called atoms Thought atoms varied in size, shape and weight BC Aristotle Opposed the Atomic Theory Thought matter was made of air, water, fire, and Earth 1808 John Dalton Atomic Theory All matter is made up of atoms All atoms of a given element are identical in mass and properties Compounds are formed by a combination of 2+ different kinds of atoms A chemical reaction is the rearrangement of atoms X Atoms are indivisible and indestructible 1897 J.J. Thomson Cathode Ray Experiments Discovered the Electron Negatively charged subatomic particle Plum Pudding Model The electrons are distributed throughout the atom with their charge balanced by the presence of a uniform sea of positive charge 1911 Ernest Rutherford Gold Foil Experiment Observation: Some alpha particles deflected to the side and back to their origin
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