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ATOMS
THE BUILDING BLOCKS OF
MATTER
The Greek Model

Democritus concluded that matter
could not be divided into smaller and
smaller pieces forever.
• The smallest piece would be obtained
and would be
.
• He named this smallest piece of matter
an
.
• He hypothesized that atoms were _____
and
made of the same material.
Dalton’s Model




All elements are composed of atoms.
Atoms of the same element are exactly
_____.
Atoms of different elements are _______.
Compounds are formed by joining of
atoms of _________ elements.
Thomson’s Model

The atom is made
of a puddinglike
positively charged
material
throughout which
negatively charged
(_______)
electrons were
scattered, like
plums in a
pudding!
Rutherford’s Model


Proposed that an
atom is mostly
empty space with a
dense, positively
charged ______in
the center.
Negatively charged
electrons were
scattered outside
nucleus.
Bohr Model


Electrons move in
definite orbits
around the
nucleus.
These orbits, or
__________, are
located at certain
distances from the
nucleus.
Wave Model



Electrons do not move around an
atom in a _______ path.
Scientists can only predict where an
electron may be.
Location is based on how much
_____ the electron has.
Modern Atomic Theory

Based on Rutherford’s Model, Bohr’s
Model and wave mechanics.
• An atom has a small, positively charged
nucleus surrounded by a large region in
which there are enough electrons to
make the atom _______.