Download The Development of Atomic Theory

Do Now – September (prime number
between 20 and 28), 2009
Please answer the following questions in
COMPLETE SENTENCES.
1. Write a sentence describing
what a theory is.
2. Why weren’t cell phones
invented when regular phones
were?
Agenda
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Do Now/Announcements
Unit 2 Test Results and Personal
Tracking
Review Theories
Read article and finish Friday’s notes
Evolution of Atomic Theory #1
Work Time (?)
Exit Ticket
Unit 2 Test Results – 2nd Period
• 100% or above
– Chris Treadway
• 90% and above
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Raul Baca
Diquan Forcell
Dalvin Hickerson
Ronald Jackson
Omar Martinez
Blake Percle
Alexandria Sierra
Brandon Toney
CLASS AVERAGES
2nd: 85
3rd: 85
Unit 2 Test Results – 3rd Period
• 100% or above
– Isaac Wallis
• 90% and above
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Patrick Beckham
Jasmine Castro
Jonathan Cordero
Christina DeArmas
Kaynetra Hunter
Angelle Johnson
De’Shawn Lemieux
Jontrel Mackey
Laronda Severance
Cachi Tran
Steven Webb
CLASS AVERAGES
2nd: 85
3rd: 85
Unit 2 Test Results – 4th Period
• 95% or above
• Other As and Bs
– Carolyn Dhanraj
– Robin Foucha
– Briana Petes
– Carlos Turner
CLASS AVERAGES
2nd: 78
3rd: 76
4th: 71
Objectives
• SWBAT describe and discuss how
theories change over time.
• SWBAT describe the evolution of the
atomic theory from 420 B.C. to 1898.
• SWBAT defend a conclusion using
research as evidence.
Review
• A theory is an explanation that has
been supported by many, many
experiments
– Supported over time
– Subject to new experimental data and
can be modified
– Used to make predictions that are
true
How is a THEORY different from a
HYPOTHESIS?
• A theory is an explanation that has
been supported by many, many
experiments
– Experiments have already been
conducted to support a theory
• A hypothesis is a tentative
explanation for observations that
have already been made
– Experiments must be conducted to test
hypothesis
CONCLUSIONS
• A conclusion is a judgment based on
information obtained in an
experiment
– Scientists apply DATA to HYPOTHESIS
to form CONCLUSION
Remember!
• A hypothesis is a tentative explanation
for observations that have already been
made
• A conclusion is a judgment based on
information obtained in an experiment
• A theory is an explanation that has been
supported by many, many experiments
(related to a scientific law)
So what is a SCIENTIFIC LAW?
• A scientific law is a description
of nature supported by many
experiments
–It is a simple description
–A theory describes how the law
works
–Theories and laws are similar
What is an ATOM?
An atom is the smallest part
of an element that retains
(keeps) the properties of the
element
Remember! Particles hold the identity of matter!
What is an ELEMENT?
An element is a pure
substance that cannot be
broken down into simpler
substances by physical or
chemical means
So How’d They Do It?
How do you think scientists learned
about the particles of a substance
when they couldn’t even see them?
In other words, how did they know
that all matter was made of tiny
particles?
Unit 3
Chemistry Secrets:
Atoms and the Periodic Table
What should we understand?
History and science are intertwined. We can look
back on history and see just how the atom and
periodic table were developed. The
atom is so central to our understanding of
chemistry because it is these particles that
determine what we can observe about all matter.
Everything is composed of atoms. Some of our
most pressing international debates today
revolve around the structure and properties of
the atom. We have to be informed of ALL
models of the atom.
Essential Questions
1) Who made the most important
contribution to the development of
atomic theory?
2) What makes one atom different from
another? How are they similar?
3) Why is it so important to understand how
the periodic table is organized?
4) What secrets can we uncover about the
elements using the periodic table?
How in the World
Did They Figure All
this Out!?!
Big Players in Atomic Theory
Democritus (460-370 B.C.)
Aristotle (384-322 B.C.)
John Dalton (1808)
J.J. Thomson (1898)
R.A. Millikan (1909)
Ernest Rutherford (1909)
Niels Bohr (1913)
Chadwick (1932)
Numero Uno! - Democritus
(460-370 B.C.)
• Experiment: Observations and Inferences
(no REAL experiment…just IDEAS)
• Where: Greece
• When: 420 B.C.
• First theory of the atom
– The “birth” of the atom
Democritus - Conclusions
•Matter is composed of tiny
particles
Named them atomos (Greek)
•Different kinds of particles
have different sizes and
shapes
Page 88
•Particles move through
empty space
Number 2 - Aristotle
(384-322 B.C.)
• Aristotle gave us this quote…
– “We are what we repeatedly do.
Excellence, therefore, is not an
act but a habit.”
• Among other things…
– He challenged the ideas of
Democritus
– He did not think the
“nothingness” of empty space
could exist
Page 88-89
Coming in Third…
John Dalton (1766-1844)
•Experiment:
Careful chemical
measurements
•Where: England
•When: 1803
Page 90
Four Postulates
• All matter is made of tiny
particles called atoms.
• All atoms of a given
element are identical, but
they differ from those of
any other element.
Four Postulates
• Compounds are formed by
a combination of 2 or more
types of atoms.
• Chemical reactions occur
when atoms are rearranged.
John Dalton’s
Conclusions
•Dalton thought
that atoms were
hard, round,
solid balls
(like marbles)
Cuatro! J. J. Thomson (1856-1940)
•Experiment: Cathode
ray tube
•When: 1898
•Where: England
E
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CONCLUSIONS
•He said the atom was a ball of
positive charge with electrons evenly
spaced in the atom
•Atoms can be divided into smaller
SUBATOMIC particles!
Compare and Contrast
What are the similarities and
differences between each
contribution?
How did each theorist add to or reject
the discoveries or ideas developed
before him?
RAFT - Independent Work Time
R = Role
Pretend to be either Dalton or Thomson.
A = Audience
You are writing to inform everyone of your
discoveries!
F = Format
Letter, Newspaper column, or Rap
T = Topic
Details of your discovery and how you know it is
true - YOU HAVE “WORKED”
HARD…DEFEND YOUR RESEARCH!
You may use a chemistry book to help.
Exit Ticket
1. Can people think that theories are correct even
when they are not? How does this happen?
How is it that theories change?
2. What was Dalton’s biggest contribution to
atomic theory?
3. If you achieved the class average on your test,
what did you do to get that grade and how will
you continue in the future? If you did not get
the class average on your test what will you do
differently next time to make sure that you do
better?
Cinco!
R. A. Millikan
• Experiment: Millikan Oil Drop
Experiment
• When: 1909
• Where: U.S.A!!!!
Conclusion:
Electrons have negative charges!!!
Number Six!
Ernest Rutherford
• Experiment: Gold
Foil Experiment
• When: 1910
• Where: Montreal
Ernest Rutherford
• Conclusions:
• Discovered and
named the nucleus
• Protons and mass
concentrated at
center of atom
• Performed the
alpha-scattering
gold foil experiment
http://micro.magnet.fsu.edu/electromag/java/rutherford/
More History
Ernie’s (Rutherford) Big Adventure
Thin Sheet of Gold
Atoms
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Rutherford’s Conclusion
• Atoms are made of mostly
EMPTY SPACE!
– Actually, the ratio of the
size of the nucleus to the
diameter of the orbits of
electrons can be compared
with placing a marble in the
middle of a football
stadium!
Empty Space Continued
• “Neutrons and protons occupy the atom's
nucleus. The nucleus of an atom is tiny -- only
one-millionth of a billionth of the full volume
of the atom -- but fantastically dense, since it
contains virtually all the atom's mass. As
Cropper has put it, if an atom were expanded
to the size of a cathedral, the nucleus would be
only about the size of a fly -- but a fly many
times heavier than the cathedral.” -A Short
History of Nearly Everything by Bill Bryson
Assignment: RAFT
• Option 1: Rap
• Role: An atomic Theorist
• Audience: Writing to another atomic
theorist
• Form: an appropriate rap
• Topic: Why your theory and model is better
than theirs
+3 points for presenting on Monday
Assignment: RAFT
• Option 2: Polite, Formal Letter
• Role: An atomic Theorist
• Audience: Writing to another atomic
theorist
• Form: a formal letter
• Topic: Politely stating why your theory and
model proves theirs wrong
+3 points for presenting on Monday
Assignment: RAFT
Things to Include
• Personal information about both theorists where they’re from, physical appearance,
etc.
• All necessary facts about both theories or
models
• How the theory is better than the one that
came before it
I’d like you to meet my friend, and
your newest friend in Chemistry…
The Periodic Table of Elements
On the periodic table there are
letters that symbolize the elements.
• An element is a substance that is made up
of the same type of atom.
• Example: Aluminum. An aluminum can is
made up of TONS of atoms. They are all
aluminum particles.
Periodic Bingo
• Place a dot on the element as it is called.
See if you can get BINGO!!!!
Atomic Number = Defines the atom
• Top Number OR always the smaller
number
• Equals the Number of protons in the atom
Which element has the atomic
number???
•6
•13
•35
Which element has the atomic
number???
•10
•82
•47
Atomic Mass = mass of the nucleus
• Bottom Number  OR always the bigger
number
• Equals the number of protons and
neutrons
Which element has an atomic mass
of…
•12
•27
•11
Which element has an atomic mass
of…
•56
•31
•238