Download Atomic Model Evolution (Webquest)

Atomic Model Evolution (Webquest)
Directions: Research and look up the many experiments on that have lead to the current model of the atom. If you feel this sheet will
not give enough room you can set this up in your lab-book without using this page. Be as clear and specific as you can. When
complete please tape into lab-book for future reference.
LT: IWBAT describe the evolution of the atomic model, which includes stating how the scientists knew they were right
(evidence vs inference).
Name of
Scientist/Year/Name
of Experiment
Democritus
~460BC
John Dalton
1803
“Various Experiments
with Vapor,
Temperature and
Pressure”
Observations/Evidences from
Experiment
Inference(s)
(What did they learn?)
-no experiment done
-he philosophized that all matter was made up of small units that
couldn’t be broken down any further while maintaining the same
properties, he called each small unit an “Atom”.
- he predicted the Atom was a solid ball with no electrical properties
(no positives or negatives)
5 Points to Atomic Theory…. (explain each)
1) all matter is made up of atoms
2) all atoms in a given element are
identical
3) atoms are indivisible/industructable
while still maintaining the same
properties
4) a chemical reaction is a rearrangement
of atoms that come in specific ratios
(compounds are made up of 2 or more
atoms)
Picture of Atomic Model
JJ Thomson
1898
“Cathode-Ray Tube
Experiment”
Ernest Rutherford
1911
“Gold Foil Experiment”
Stream of particles that
attracted to a positive
plate and repelled the
negative plate
He took helium atoms
(alpha rays--positive)
and shot it at a piece of
gold foil
1) some particles
went straight
through
2) some particles
bounced back but
to the sides
3) some particles
bounced straight
-the stream of
particles had a
negative charge
-atoms have a
particle that is
small and negative
“electron”
*Plum-Pudding
Model*
1) atoms have a
dense nucleus
that is
positive
2) atoms are
made up of
mostly empty
space
back
Niels Bohr
1913
“Spectroscope and
Spectrum Lines”
James Chadwick
1932
“______________”
Erwin Schrodinger
1933
“______________”
He looked at element
tubes and drew the
spectrums for many
different elements
1) that each
element has
different numbers
of electrons and the
electrons are on
different energy
levels
He did many radiation
experiments, he took
polonium and smashed
with beryllium
-He found the
neutron
-Mathematical formulas are used to match
the kinds of data that was being observed.
-Mix geometry with statistics
Inferred: that electrons don’t orbit the
nucleus, they move like waves in an electron
Quantum Mechanical
Model – several
scientists
*the current model
cloud.