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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
__________________________.