Data Table of Atomic Model Info…
Name of Scientist/Year/Name of
Experiment
Evidence/Observations
from Experiment
Inferences Made from the
Evidence
Democritus
460 BC
NO experimentation or
direct evidence.
Stated/theorized atoms
were indestructible
spheres. He theorized that
if you cut something in half
over and over, eventually
you would be left with
something that could not
be broken down “atomos”,
or nothing.
John Dalton
1766-1844
Gas Experimentation
Researched that gases
could only combine in
certain proportions.
1. All matter is made of
atoms.
2. Atoms cannot be
subdivided, made or
destroyed.
3. All atoms of the
same element are
identical; different
elements have atoms
with different
properties.
4. Chemical reactions
occur when atoms
are rearranged.
5. Compounds are
combinations of
atoms in simple,
whole number ratios.
Picture and Name of Atomic
Model
Which type of
model is it?*
(Physical or
Conceptual)
Conceptual
“Atomos”, uncuttable
Billiard Ball
Conceptual
Joseph John Thompson
1897
Cathode Ray Tube
Passed a beam of
electricity through a
Cathode Ray Tube. The
beam bent toward a
positively charged plate. It
took A LOT of electricity
to get an effect.
Atoms are made of both
positive and negative
charges that are neutral if
equal.
Plum Pudding
Conceptual
Planetary Model
Conceptual
Charges are distributed
equally throughout the
atom.
The negatively charged
parts (electron) are VERY
tiny, because it took a huge
amount of negatively
charged particles to bed
toward the positively
charged plate. **For the
plate to have positive parts
too!
Coined the term “electron”
Ernest Rutherford
1911
Gold Foil Experiment
Launched alpha
(positively charged)
particles through foil.
Most particles went right
through and some were
deflected.
There is a dense core of
positively charged particles
(proton), because the
deflection in multiple
directions of right back
represented similar
repelling.
Most of the atom is made
of empty space, because
most of the time the
Neils Bohr
1913
Spectroscopy
Every element gives of
different frequencies of
light when viewed
through a spectroscope.
Each frequency of light
represents a different
energy level.
particles launched went
right through!
Knew Rutherford’s model
was flawed, as all electrons
would eventually be drawn
to the nucleus and that
does not happen.
Bohr’s Model of the Atom
Conceptual
Electron Cloud Model
Conceptual
Mathematical
Electrons exist and travel in
specific orbits or energy
levels.
When electrons are
energized they jump and
absorb energy as they go up
and release energy as light
when they fall.
The frequency of light
emitted represents the
jumping from different
energy levels.
Erwin Schrodinger
1926
Mathematical Equations
Used mathematical
equations to determine
the likelihood of the
location of the atom.
Since the location of the
electron could only be
predicted, he determined
that electrons existed in
clouds around the electron.
Where the electron cloud is
the most dense, the more
the likelihood you can find
the electron there.
Sir James Chadwick
1932
Bombardment of Beryllium
Launched alpha particles
(positively charged) at
Beryllium. The neutrons
from the Beryllium
knocked into the wax
paper. The protons then
emerged from the wax
paper in a straight line.
Neutrons, a neutral particle,
had to exist as the protons
were knocked in a straight
line and not deflected at
any angles. This straight
line would only be
produced by a neutral
particle.
Conceptual