Download Development of atomic model

I wonder:
What is
Matter?
Name ____________________________
Teacher _______________Hour _______
IPS website: http://www.mononagrove.org/faculty/ips/index.cfm
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Unit Summary
Content Based Goals
Learning Goal
Students can
define the four
element theory
Activity(s)
Observed
-Alchemy
presentation
and notes
Big Ideas
•
The four element theory states that all matter can be broken down into
four main substances:
1. earth
2. air
3.
4. water
5. fire
Pseudoscience (def.): a practice that claims to be scientific but does not
properly follow the scientific method.
How to identify pseudoscience: (write in at least 2)
o Does not fit the 3 criteria: PBS
o Use of vague, exaggerated, or untestable claims
o Over reliance on confirmation rather than contradiction
o Lack of openness to testing by other experts
o A
o bsence of progress
o Personalization of issues
o Use of misleading language
Protons are positive (+)and located in the nucleus.
Neutrons re neutral (0) and are located in the nucleus.
Electrons are negative (-) and are located in the shells and have virtually
no mass.
Students can
explain the
difference
between
science and
pseudoscience
-Alchemy
presentation
and notes
Students
understand
and can
describe
sub-atomic
structure
-Sub-Atomic
Timeline
Students
observe how
models
change over
time
Students can
identify the
importance,
relevancy, and
an example of
Indirect
Measurement
-Sub-Atomic
Timeline
•
The model of the atom as we know it today is the result of many
modifications and additions
-Gold foil
experiment
-Indirect
Measurement
Intro
•
Indirect measurement (def.): A technique that uses calculations to find a
measurement when direct measurement is not possible.
o Ex) how we know what we know about atoms even though we
cannot see them directly
•
•
-Science vs.
Pseudoscience
activity
•
•
•
•
-Nuclear
Marbles
-Gold foil
experiment
Skills Based Goals
Learning Goal
Students can Select a simple hypothesis, prediction, or conclusion
that is supported by a data presentation or a model E.20.1
Students can Identify key issues or assumptions in a model E.20.2
Activity Observed
-EPAS practice (separate sheet)
-EPAS practice (separate sheet)
-Gold foil experiment
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During the following PowerPoint and demonstrations, fill in the blanks below with the words that are both BOLD and
CAPITALIZED on the slides.
The Structure of Matter: A Historical Perspective
Prehistoric times
•
Before 1000 B.C.E.
•
People thought about matter for its ________________, not about what it was made of.
•
They thought: “This could make a nice arrowhead,” not, “I wonder what makes this rock hard and shiny?”
Greek Theories
•
The Greeks were ____________________________, not scientists.
•
Because they had become “civilized,” they had more time to sit around, _________________ about, and
________________ what matter was.
•
They did not do experiments.
Thales – 600 B.C.E.
•
Thought that the simplest form of matter was _______________.
•
He thought: Everything comes from water and depends on water; therefore water must be the
most basic of substances.
Anaximenes – 550 B.C.E.
•
•
Thought that the simplest form of matter was _______________.
He thought: Air can be condensed to form solids like the earth or can exist as we know it.
Heraclitus – 500 B.C.E.
•
•
Thought that the simplest form of matter was _______________.
He thought: All things are composed of fire and are again resolved into fire.
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Empedocles – 450 B.C.E.
• _______________________ the ideas of the Greeks before him but added _______________
as a component.
• Developed the _________________ _________________ __________________:
– All matter is made of 4 basic substances:
• ______________, ______________, _____________, and _____________.
Leucippus (the teacher) & Democritus (the student) – 450 B.C.E.
•
Something cannot come from nothing.
•
All matter is made of indivisible, indestructible ______________________ (____________)
•
They thought: “The properties of a material are due to the arrangements of its atoms in
space.”
Democritus added:
•
•
Atoms are in _____________________ ______________________.
The __________________ of atoms determine their properties:
– Ex)
• Sour foods have sharp atoms.
• Sweet foods have large and round atoms.
Aristotle – 350 B.C.E.
•
•
Disagreed with the atomic theory.
Supported the 4 element theory and added the ____________ ______________________:
_______________, _______________, ______________, and ________________.
•
Because he was known as the ________________ _____________________ in many things,
people had to believe him, and did so for 2000 yrs!!!
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Alchemy
•“_______________________ __________________________”
•Studied in many cultures from 5000 B.C.E. to present.
•It is a ____________________________________: _______________________________________________
_________________________________________________________________________________
•They develop models that do not fit the 3 criteria of a good model.
•Very secretive
The Philosopher's Stone
•
The alchemists thought if they could find or create this substance, they could find or create their
three main goals:
1) __________ ______________________ _______ ___________________
•
The _____________________ _______ ______________ that allows you to
live forever
•
This would be worth ________________.
2) ____________________________ _______________________
•
•
A liquid that would ____________________ ____________________
This would be worth ________________.
3) ____________________________ _______ _________ ___________________
•
•
_________________ cheap _____________ into silver and gold (Ag and Au).
This would be worth ________________.
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Alchemists’ Contributions to Science
1) Discovered five ______________________: P, As, Sb, Bi, and Zn
The “ancients” already knew about: Au, Ag, Hg, Pb, Fe, Cu, Sn, and C
2) Produced a variety of ___________________________: test tubes, flasks, etc.
3) Refined and discovered ways of making things _____________: distillation, crystallization
4) Discovered ways of working with _________________: alloying
Post-Alchemy: The Beginning of Science
First Correct Recognition of an Element
•
Even though ancients and alchemists knew of some elements, some
substances were incorrectly identified as elements.
• ____________________ ____________________ (1661)
– Developed the definition of an element.
– _____________________: __________________________________________________________
_______________________________________________________________________________.
– Ex) Water can only be broken down into O and H.
The Father of Modern Chemistry
• ____________________ ___________________ (1789)
–
Had a _____________ of 23 substances, 21 of which are correct
with the elements we know today.
–
Introduced _____________________________ ______________________________.
i.e. using numbers
Today, the story continues…
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Homework - IPS
Development of the Model of Matter
1) We studied three groups of individuals in the development of the model of matter: Greek Philosophers,
Alchemists, and Scientists. Draw in the range of time that each group studied the model of matter on the
timeline below:
I
I
I
I
I
I
I
I
I
I
I
I
I
600
B.C.E.
500
B.C.E.
400
B.C.E.
300
B.C.E.
200
B.C.E.
100
B.C.E.
0
100
A.D.
1600
A.D.
1700
A.D.
1800
A.D.
1900
A.D.
2000(present)
A.D.
2) Who was considered the “great authority?” __________________________________
3) Empedocles and Aristotle had similar ideas about matter. What aspect of their theories do they share?
______________________________________________________________________________________
______________________________________________________________________________________
4) What are the 4 elements represented in the Four Element Theory?
a. ______________________________________
b. ______________________________________
c. ______________________________________
d. ______________________________________
5) Of the Greeks, which 2 individuals are responsible for the theory that still fits our model of matter today?
______________________________________________________________________________________
6) Alchemy is a pseudoscience. Describe what this means in a complete sentence and in your own words:
______________________________________________________________________________________
______________________________________________________________________________________
7) List the 4 contributions alchemists have made to science
a. ________________________________________________________________________________
b. ________________________________________________________________________________
c. ________________________________________________________________________________
d. ________________________________________________________________________________
8) Define the term “element”? ________________________________________________________________
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Science vs. Pseudoscience
As a growing consumer of information and products, it will be an important skill for you to be able to distinguish
between science and pseudoscience. Your teacher will provide you and your group with one of six ways you can
identify a pseudoscience. In addition, you will be given a reading about a topic that is considered a pseudoscience.
Your team’s job is to present to the class how your pseudoscience can be identified as such. After each
presentation, we will summarize the main ideas in the chart below.
SCIENCE
Definition:
vs.
PSEUDOSCIENCE
Definition:
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Review of the Atomic Model
As you learned in science class last year, all matter is made of _________________________. The Greek
philosophers Leucippus and Democritus were the first to propose this model of matter. Our model of matter has
come a long was from the Greek’s ideas about atoms. You may have also heard about the famous chemist John
Dalton.
Dalton was the first person to weigh an atom. Of course, he could not pick up an atom and weigh it on a
balance. How then did he arrive at the atomic weights listed in the periodic table? He thought that if he weighed
larger amounts of the elements, and if these amounts contained the same number of particles, then he could weigh
one atom relative to another. He chose hydrogen to be the standard (1amu) and weighed the other elements based
on hydrogen’s weight. Dalton said that since Hydrogen is the lightest atom, it must also be the smallest in size. He
published this first list of atomic weights in 1805.
Overall, even though
Dalton was not a good
experimenter, he was a brilliant
thinker. His faith in the existence
of atoms contributed much toward
promoting the Atomic Theory. In
fact, atoms were so real to him
that he could imagine their shape
and size, he could write symbols
showing how they combine and
he could even weigh them.
Dalton’s firm belief in atoms got
others to believe his model as
well. Today Dalton’s contributions
can be summed up as follows:
Modern Periodic Table
ATOMIC THEORY MODEL:
1. All matter is made of atoms that are ________________________.
2. All the atoms of ______________ ______________ are alike in weight and in all other properties.
3. The atoms of _____________ ______________ have different weights and properties.
4. Atoms are indestructible and preserve their _______________________ in all chemical reactions.
Visualizing the Atom
Atoms are so small that scientists still have not been able to ___________ _____ ________. Using
advanced computers, we can use STM (scanning tunneling microscopy) imaging. The computer then generates a
visual ___________________ of the atom(s). Your teacher will now show you some of these amazing images.
Draw or describe one of the images in the space below.
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Homework - IPS
Pseudosciences
Choose one of the following pseudosciences, do a little research, and fill in the graphic organizer bellow:
1.
2.
3.
4.
Lunar Effect
The Bermuda Traingle
Dowsing
Crystal healing
Topic:
Description:
One way to identify a pseudoscience:
Another way to identify a pseudoscience:
Describe how your chosen pseudoscience can be identified by
the method above:
Describe how your chosen pseudoscience can be identified by
the method above:
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TIMELINE: Development of the Sub-Atomic Theory
Around 460 B.C., the Greek philosopher Democritus asked: If you break a piece of matter in
half, and then do so again and again, how many breaks will you have to make until you can
break the matter no more? Democritus reasoned that one would eventually end up with the
smallest possible bits of matter. He named these basic matter particles atomos, or atoms. The
idea that matter is made up of fundamental particles called atoms is known as the Atomic
Theory of Matter. Recall though that the ideas of Democritus were opposed by Aristotle and were not commonly
considered until more than 2,000 years later.
It was not until the 1800’s that British chemist John Dalton began to revive the atomic theory of
matter by sharing the results of his experiments with others. Using various chemicals, Dalton
demonstrated that matter seems to consist of atoms. He published The Theory of the Atom in
1808, explaining that each element is made of small atoms of a certain type. He also proposed
that different elements have atoms of different masses. Dalton imagined atoms as tiny, solid
balls. Most importantly, he stressed that atoms were indivisible particles of an element. The true structure of atoms,
and thus the things that made them up, were still yet to be discovered.
In 1898, English physicist J.J. Thomson proposed a revised model of the atom. He had
discovered a subatomic (part of an atom) particle and called it an electron. Thomson reasoned
that since electrons carry a negative charge, the rest of the atom must be positively charged.
When he drew a representation of his atomic model, he drew a picture resembling raisins
(electrons) stuck in a muffin (positive area). Since he experimented with a variety of substances,
he concluded that atoms of different elements contain different numbers of electrons.
In 1904, the Japanese chemist Hantara Nagaoka proposed a model of the atom that had a large,
positively charged sphere in the center with electrons revolving around the sphere. His representation
was much like a picture of our solar system, with small planets revolving around a much larger sun.
Seven years later in 1911, New Zealand physicist Ernest Rutherford performed an experiment in
which he aimed atomic particles at a thin sheet of gold foil. He found that most particles passed right
through the foil, but some bounced back. These results suggested a model that most of an atom is
empty space. The data also suggested that almost all of the mass of an atom is contained in a tiny
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nucleus. Rutherford affirmed the idea that the nucleus was positively charged, and offered that the positive charge
was a result of the subatomic particles called protons, which he had discovered. Rutherford disagreed with Nagaoka,
however, and thought that the electrons of the atom moved more randomly around the nucleus than the sphere
shaped path Nagaoka thought of.
In 1913, Danish physicist Niels Bohr insisted that electrons are not randomly located around the
nucleus, as Rutherford had thought, but were moving in specific spherical paths, or shells. In this
way, his representation was similar to the “solar system” model proposed by Nagaoka. Bohr was
actually able to calculate the distance between the nucleus and first energy shell and concluded
that all shells are at fixed distances from the nucleus. He said that atoms absorb or give off energy
when the electrons move from one shell to another.
At this point, it was a commonly accepted model that atoms were made of protons (positively
charged) and electrons (negatively charged) in equal numbers. In 1932, British physicist
James Chadwick discovered another subatomic particle, the neutron. He found the neutron
to have the same mass as a proton, but with no charge. The existence of the neutron
explained why atoms were heavier than the total mass of their protons and electrons AND
why atoms were neutral, overall, in charge.
The current model of the atom has resulted from further revisions of
those proposed in the past. Scientists working from the 1940s to the
3n0
present have developed the model that we accept today. Presently, the
scientific model says that atoms have a heavy, small, positively charged
nucleus made of protons and neutrons. The electrons are thought to
form a negatively charged “cloud” of sorts around the nucleus and it is
impossible to determine exactly where an electron is at any given time.
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Sub-atomic Structure Timeline
What the scientist discovered:
406 BC
1808
What part of their model did we keep?
Democritus
John Dalton
1898
J.J. Thompson
1904
Hantara Nagaoka
1911
Ernest Rutherford
1913
1932
Niels Bohr
James Chadwick
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Modern Model of Sub-Atomic Structure Notes
1. Basic Subatomic Particles and their Characteristics:
Subatomic Particle
Name
Proton
Characteristic
Symbol
Charge
Location in the atom
Discoverer
Date of discovery
Mass in grams
Mass in amu
(mass number)
2. Overall Structure of Atom
A. Nucleus
Neutron
Electron
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B. Electron orbits, shells, or energy levels
i. Elliptical path
ii. Electron cloud motion
iii. Relative distances
3. Size and Weight of the Atom – Need for new atomic size units
A. Mass
i. The atomic mass unit (amu)
•
__________ g = _____ amu
•
__________ amu = _____ g
ii. Range of masses
iii. Location of atomic mass
iv. Density of the nucleus
B. Length – the Angstrom unit (Å)
i. Diameter
a. Range of sizes
b. Diameter of nucleus
4. Visual Evidence for the Existence of Atom
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Indirect Measurement
When scientists wanted to find out what an atom was, they were not able to look directly at what an atom was made
of. They had to make inferences (educated guesses/extrapolations) from the results of many different experiments.
It was like trying to describe the picture below, with only small portions visible.
1) Write four sentences describing what you can see of the picture above.
______________________________________________________________________________________
______________________________________________________________________________________
______________________________________________________________________________________
______________________________________________________________________________________
______________________________________________________________________________________
______________________________________________________________________________________
______________________________________________________________________________________
2) What information or parts of the picture would make your descriptions more accurate without revealing the
entire picture?
______________________________________________________________________________________
______________________________________________________________________________________
______________________________________________________________________________________
VIEW “INDIRECT MEASUREMENT” POWERPOINT
Indirect measurement (def.) ____________________________________________________________________
_____________________________________________________________________________________________
146
IPS – Indirect Measurement - Nuclear Marbles Lab
Purpose: To determine the diameter of a marble by indirect measurement.
Procedure:
1. Work in groups of three (Recorder, Roller, and Returner)
2. Place nuclear marbles along wall
3. Without looking, roll the rolling marble at the nuclear marbles
4. Count and record how many trials and how many times a nuclear marble is hit by the rolling marble.
5. You must have 150 trials!
Data:
Trials
Hits
Nuclear marbles________ Rolling marble ___1____
Calculations:
Use this formula to calculate your marble diameter:
Show your calculations here:
D = HL
2TN
D = diameter
H = # of hits
L = 61 cm
T = # of trials
(150)
N = # of nuclear
marbles
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A Sophisticated Example of Indirect Measurement:
Rutherford’s Gold Foil Experiment
View the following video to introduce Rutherford’s Gold Foil Experiment:
http://nz.youtube.com/watch?v=5pZj0u_XMbc&feature=related
1) What is Rutherford measuring? _____________________________________________________________
2) Why would this be considered and indirect measurement?
______________________________________________________________________________________
______________________________________________________________________________________
Now go to the following website: http://www2.ku.edu/~quarked/parents/lesson7.html Go to ‘follow up activities.’ Click
on ‘Shape Sleuth.’ Try this activity.
3) How is this an indirect measurement?
______________________________________________________________________________________
______________________________________________________________________________________
4) How is this similar to Rutherford’s Gold Foil Experiment? _________________________________________
______________________________________________________________________________________
Look back at the Sub-atomic Theory/Structure Timeline. Notice that J.J. Thompson formulated a different model prior
to Rutherford’s model.
5) Describe J.J. Thompson’s model here: __________________________
A)
__________________________________________________________
__________________________________________________________
6) Do you think Thompson’s model explain the bouncing back of particles?
Why or why not? ____________________________________________
__________________________________________________________
__________________________________________________________
7) Which drawing to the right would best represent Thompson’s findings?
______________________________________________________
8) Which drawing to the right would best represent Rutherford’s findings?
________________________________________________________
Still having a hard time with this? Maybe this will help:
http://www.mhhe.com/physsci/chemistry/essentialchemistry/flash/ruther14.swf
B)
148
IPS – “The Development of the Atomic Model of Matter” Review
Where appropriate, answer the following questions in complete sentences.
1) Describe the two different models of matter that were developed by the Greeks. Make sure to include the
people involved in developing that model.
a. ________________________________________________________________________________
________________________________________________________________________________
b. ________________________________________________________________________________
________________________________________________________________________________
2) Explain what alchemy is and why it is not considered a science today.
___________________________________________________________________________________
___________________________________________________________________________________
3) Describe the model of the atom that Dalton developed.
___________________________________________________________________________________
___________________________________________________________________________________
a. How is it similar to the model that the Democratis and Leucippus thought of?
________________________________________________________________________________
________________________________________________________________________________
b. How is it different?
________________________________________________________________________________
________________________________________________________________________________
4) JJ Thomson changed our view of the atom.
a. What did he discover that led him to change the model of the atom?
________________________________________________________________________________
________________________________________________________________________________
b. How did he describe an atom?
_________________________________________________
Draw:
_________________________________________________
_________________________________________________
c. What part of Dalton’s model was found unacceptable based
on Thomson’s ideas?
________________________________________________________________________________
________________________________________________________________________________
149
5) Define the following: Indirect measurement—
______________________________________________________________________________________
________________________________________________________________________________
6) Rutherford indirectly measured something about the atom. Explain what he measured and how he
measured it.
___________________________________________________________________________________
___________________________________________________________________________________
What makes indirect measurements so important in science? __________________________________
___________________________________________________________________________________
___________________________________________________________________________________
7) Draw and label a diagram of the atom we will be using in class.
8) What is meant when we say that “the atom is mostly empty space?” _____________________________
___________________________________________________________________________________
___________________________________________________________________________________
9) Using the ideas of charges, the structure of the atom, and the knowledge that that atom is mostly empty
space, explain why you are not falling through the chair you are sitting on right now.
___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________