Page 162 Super Model Start a new threadtopic Learning Target How can you determine the structure of something you cannot see Update TOC Super Model Read Intro p 162163 Since we cant see an atom we are going to use different types of models to help us visualize atoms ID: 562216
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Slide1
Super Model
Page 162Slide2
Super Model
Start a new thread/topic
Learning Target: How can you determine the structure of something you cannot see?
Update TOCSlide3
Super Model
Read Intro p. 162-163
Since we can’t see an atom, we are going to use different types of models to help us visualize atoms.Slide4
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Read
What is a Model
p. 167
Yes, you need to take notes!
Physical model –
Conceptual model –
Mathematical model –
Inferences – Slide5
Physical Model
Physical model
– reproduces an object on a different scale. Examples: Slide6
Conceptual Model
Conceptual model
– describes a system and shows how the various components of the system interact
Examples: Slide7
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An atom is best described using a
Conceptual model
it helps us to understand how the parts interact.
Nobody knows what the structure of an atom really looks like!Slide8
Mathematical model
Mathematical model
– is a subset of conceptual models where mathematical relationships are used to describe a system.Slide9
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We are going to look at the history of our understanding of atoms and the scientists that contributed to that knowledge.
Who was
Democritus
and what was his big idea?Slide10
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Democritus
was a Greek philosopher and scientist from ~
460BC
.
He was the first to think about the particles that made up matter and called them “atoms”.
His model: Slide11
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John Dalton
–
1803
– proposed first atomic theory.
An atom is an indivisible, indestructible, tiny sphere. Determined that elements have unique atomic masses.
His model: Slide12
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Joseph John Thompson
– read p. 170-171 Take NOTES and answer these questions!
In what year did Thomson make his major finding?
Summarize Thomson's experiment. (A sketch or two might be nice!)
What
was Thomson
trying to determine?
What surprising discovery did he make?
What conclusion did Thomson make?
What evidence did he use to support his conclusion?Sketch Thomson's model of the atom.Slide13
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Joseph John Thomson
– 1856-1940
In 1897, Thomson was experimenting with electricity, trying to figure out what was happening when electricity flowed through a wire.Slide14
Joseph John Thomson 1856-1940
Was trying to figure out what “cathode rays” were made ofSlide15
Joseph John Thomson – 1856-1940
Discovered that “cathode rays” would bend towards a positively charged plate.
Concluded that the
particles that make
up the cathode rays
must be negatively charged.Slide16
Joseph John Thomson 1856-1940
He calculated that the mass of the negative particles was 1/2000 of the mass of a proton.Slide17
JJ Thomson 1856-1940
He came up with the “plum pudding” model of the atom.
Tiny electrons equally
d
istributed throughout
t
he positively charged
“pudding” of the atom.Slide18
Entry Task
Who came up with the “plum pudding” model of the atom?
Who said that atoms are the smallest units of all matter (atoms cannot be further divided)?
Who discovered the electron?
Who said that each element has a unique atomic weight?Slide19
Rutherford Roller
Can you determine the
shape
and
location
of the unknown object under the cardboard?
You may not look underneath!
You can only roll marbles under the cardboard to figure out what’s there.Slide20
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Ernest Rutherford
– read p. 164--165 Take NOTES and answer these questions!
In what year did
Rutherford
make his major finding?
Summarize
Rutherford's
experiment. (A sketch or two might be nice!)
What was Rutherford expecting to happen?
What surprising discovery did he make?
What conclusion did Rutherford make?What evidence did he use to support his conclusion?
Sketch
Rutherford's
model of the atom.Slide21
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Ernest Rutherford
– 1871- 1937
Began as a graduate student in Thomson’s lab.
Eventually he had his own lab and was investigating the structure of the atom.Slide22
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Ernest Rutherford
– 1871- 1937
His famous experiment is known as the Gold Foil Experiment.Slide23
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Ernest Rutherford
– 1871- 1937
Based on the plum pudding model of the atom, Rutherford expect the alpha particles to go straight through the foil
undeflected
.
But
did they
???Slide24
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Ernest Rutherford
– 1871- 1937
What he saw (evidence)
What
he concluded (Inference)
Most of the alpha particles went straight
through the foil (
undeflected
)
The atom is mostly empty
spaceVery few alpha particles bounced straight back (or at a large angle)
The atom has a very small,
very dense center (nucleus)
Some
alpha particles were deflected at a an angle.
The nucleus must have a positive charge, since the positive alpha particles that came close to the nucleus
were deflected at a small angle.Slide25
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Ernest Rutherford
– 1871- 1937Slide26
Analogy Table
Feature of Rutherford Roller investigation
Piece of evidence from the Gold Foil
Experiment
Because
The cardboard
is like
Gold foil
Because alpha
particles are shooting into it.
The
marble is likeAn alpha particle
Because it shoots towards atoms in gold
foil
The line that the
marble travels is like
The unknown object under the cardboard is like
The marbles that shoot straight through without veering are like
The marbles that veer at a small angle are like
The marbles that bounce backwards are likeSlide27