Atomic Theory
Atomic Theory:
Imagine a world without the presence of atoms.
There wouldn’t be a world. There wouldn’t be
people. There wouldn’t be anything. As we learned
earlier, matter is anything that takes up space and has
mass.
Both of those characteristics can be
contributed to the existence of atoms. Without
atoms, there would be no matter. Therefore, atoms
matter!! Hahahahaha, get it??
Throughout this unit we will look at atoms and
the parts inside them; protons, neutrons, and
electrons. We will also spend some time looking at
the history of atoms and the scientists responsible for
discovering each particle.
We will also have the opportunity to look at
isotopes and the role they play in chemistry. There
are many things isotopes are responsible for including
radiation, both good and bad, as well as creating other
elements as an isotope undergoes decay. However, if
it weren’t for isotopes we wouldn’t have a number of
the medicines, and other materials we enjoy today.
Toward the end of the unit we will look at the
significance of the atomic theory and how electron
location plays a significant role in how an atom will
behave in its environment.
All the videos will be posted on YouTube and can be
accessed using multiple sources. The videos have
been formatted to work on iPhones, iPads, Android
phones, Kindles, and Nooks. The titles of the videos
are listed below so that you can search them, and the
creator of the videos should be NRHSChemistry.
Lesson Target(s) for Each Video:
Video 1 – Dalton’s Atomic Theory

I can analyze Dalton’s atomic theory for inaccuracies.
Video 2 – Structure of Atoms
 I can identify the components that make up an atom.
Video 3 – Rutherford’s Gold Foil Experiment
 I can explain the significance of Rutherford’s
contributions to the modern model of the atom.
Video 4 – Atomic Models
 I can compare the various models of the atom.
Video 5 – Isotopes
 I can identify different isotopes of the same element.
Video 6 – Atomic Mass Units
 I can calculate the average atomic mass of an element.
Video 7 – Electron Configuration
 I can construct an electron configuration when given
an element.
Video 8 – Orbital Notation
 I can demonstrate the use of orbital notation.
Video 9 – Exceptional Configurations
 I can illustrate the differences in electron
configurations.
Video 10 – Wavelength & Frequency
 I can calculate the wavelength and frequency of light.
 I can classify light based on its wavelength.
Video 11 – Production of Light
 I can distinguish between various types of

electromagnetic energy.
I can apply the significance of the Heisenberg
uncertainty principle to modern model of the atom.
Essential Learning Outcomes:
1.
2.
The model of the atom explains experimental
observations.
An atom’s electron arrangement determines its chemical
properties and periodicity.
Required activities:
Important Vocabulary
 Due dates are in parentheses
□ Atomic Theory P.S. 1-9
o
o
o
o
□
Atomic Theory P.S. 10-13
o
o
□
Video 7 – Electron Configuration
Video 8 – Orbital Notation
Video 9 – Exceptional Configurations
Atomic Theory P.S. 21-25
o
o
□
Video 5 – Isotopes
Video 6 – Atomic Mass Units
Atomic Theory P.S. 14-20
o
o
o
□
Video 1 – Dalton’s Atomic Theory
Video 2 – Structure of Atoms
Video 3 – Rutherford’s Experiment
Video 4 – Atomic Models
Video 10 – Wavelength & Frequency
Video 11 – Production of Light
.Indirect Evidence Lab
o
□
Atomic Structure Lab
o
o
□
Lab Report
Peer Review of Report
Lab Report
Atomic Theory Unit Quest
(9/23)
(9/20)
(9/21)
(9/22)
(9/22)
(9/23)
(9/23)
(9/27)
(9/27)
(9/29)
(9/30)
(10/3)
Ch. 4 Terms
 Atom
 Atomic mass
(9/26)
 Atomic mass units (amu)
 Atomic number
(9/30)
(10/4)
(9/20 to 9/23)
(9/30)
(9/28 to 9/30)
(10/3)
(10/7)
(10/5)
Ch. 5 Terms
 Amplitude
 Atomic Emission
Spectrum
 Atomic orbital
 Dalton’s Atomic Theory
 Aufbau principle
 Electromagnetic
radiation
 Electron configurations
 Electron
 Energy levels
 Group
 Frequency (ν)
 Isotopes
 Ground state
 Heisenberg uncertainty
principle
 Hertz
 Cathode ray
 Mass number
 Neutron
 Nucleus
 Period
 Periodic table
 Proton
 Hund’s rule
 Pauli exclusion
principle
 Photons
 Quantum mechanical
model
 Spectrum
 Wavelength (λ)
Additional Resources:
Animations and Demonstrations:
1) http://www.mhhe.com/physsci/chemistry/essentialchemistry/flash/ruther14.swf
2) https://www.youtube.com/watch?v=5pZj0u_XMbc
Practice Problem Websites:
1)
2)
3)
4)
http://www.quia.com/rr/70834.html
http://preparatorychemistry.com/Bishop_comp_electron_config_Flash1.htm
http://www.quia.com/quiz/715095.html
http://drmadscientist.wordpress.com/2013/06/24/wavelengthpracticeproblems/
iPhone and iPad apps:
There are none that I could find….if you find one and feel it is useful, please let me know!!!
Chemistry
Problems and Questions
Atomic Theory
Name:
Hour:
Directions:
Answer the following questions using complete sentences when necessary. On numerical problems,
show all work, circle your answers, and follow all rules of significant figures for full credit.
1. a) What are some properties of cathode rays.
b) What forces can deflect cathode rays?
2. In your own words, state the main ideas of Dalton’s atomic theory.
3. Describe which parts of Dalton's theories are not supported by our current atomic theories.
4. Describe Thompson’s and Millikan’s contributions to atomic theory.
5. Describe each model of the atom. Include the year in which they were proposed and who was credited with the
hypothesis.
6. a) What evidence lead Rutherford to believe that the nucleus of an atom was hard?
b) What evidence lead Rutherford to believe that the nucleus of an atom is positively charged?
7. What could be wrong with the statement "Atoms of an element are electrically neutral"? Explain why you chose your
answer.
8. a) Why was the neutron so difficult to discover? Explain your answer thoroughly.
b) Explain how the neutron was discovered and who discovered it.
9. State the number of protons, neutrons, and electrons in each of the following elements:
a) P
b) Sr
c) Pb
d) U
10. Name three ways that isotopes of an element differ from each other.
11. Uranium has three isotopes with the following percent abundances: Uranium-234 (0.0058%), Uranium-235 (0.71%),
and Uranium-238 (99.23%). What will be the average atomic mass of uranium?
12. Lead has four isotopes with the following percent abundances: Lead-204 (1.37%), Lead-206 (26.26%), lead-207
(20.82%), and Lead-208 (51.55%). Find the average atomic mass of lead.
13. Calculate the average atomic mass of magnesium using the following data for three magnesium isotopes.
Isotopes
Fractional abundance
a) Magnesium-24
0.7870
b) Magnesium-25
0.1013
c) Magnesium-26
0.1117
14. How would Bohr answer a student that states that an electron traveling in a circular orbit would eventually radiate
energy and fall into the nucleus?
15. Write the electron configurations of the following elements.
a) Boron-10
b) Manganese-55
c) Bromine-81
16. Explain what is wrong with each of the following electron configurations.
a) 1s2 2s2 2p5 3s2 3p3
b) 1s2 2s2 2p6 3s2 3p6 3f14 4s1
c) 1s2 2s2 2p6 3s3
d) 1s2 2s2 2p6 3s2 3p5 4s2 3f12 4p5
d) Uranium-235
18. Write the orbital notation of the following ions.
a) Ca
b) Br-1
c) Zn+2
19. Summarize the importance of orbital stability to elements and ions.
20. Explain the difference between an orbit in the Bohr model and an orbital in the quantum mechanical model of the
atom.
21. On an atomic level, how is light produced?
22. What theory could be proposed because of the Lyman, Balmer, and Paschen series?
23. A wave of radiation has an energy of 3.40x10-4 m. What is the frequency of this radiation wave?
24. A wave of radiation whose frequency is 1.50x1013 Hz is traveling at the speed of light.
a) What is the wavelength of the radiation?
b) What type of radiation is it?
25. Explain the implications of the Heisenberg uncertainty principle and how it relates to our understanding of the
modern model of the atom. Give an example showing the Heisenberg uncertainty principle in action.
Introduction:
Isn’t it amazing that scientists have been able to determine so many things about atoms without actually seeing
them? They use what’s called indirect evidence.
You use indirect evidence all the time. For example, if you find mail in your mailbox at home, you know that the
mail person has been there. You can conclude that without ever seeing him or her.
Scientists do the same thing all the time. You have learned that Rutherford was able to draw conclusions about
the atom through his gold foil experiment. His analysis of what happened to those alpha particles lead him to conclude
that the atom was mostly empty space with a dense positively charged center area called the nucleus. He never saw the
atom with his eyes yet his experiment allowed him to imagine what it must look like.
In this lab, you too will use indirect evidence. Your job is to determine the size (diameter) of a marble without
actually measuring it. You might say, “why won’t we just measure it with a ruler?” Well, that would be no fun. Besides,
how else can I convince you about indirect evidence unless you actually use it to measure what we’ll pretend is
unmeasurable? You might be surprised how close you come to the “right” answer indirectly.
Your Task
Determine the diameter of a marble by using indirect evidence.
The guiding question of this investigation is, What is the diameter of a marble?
Materials
You may use any of the following materials during your investigation:
Equipment




Wood box
Marbles
Tape
Meter stick
Safety Precautions
Follow all normal lab safety rules.
Investigation Proposal Required?
 Yes
 No
Getting Started
To answer the guiding question, you will need to design and conduct an investigation. To accomplish this task, you must
determine what type of data you need to collect, how you will collect the data, and how you will analyze the data.
To determine what type of data you need to collect, think about the following questions:
o How will you be able to identify a substance based on a flame test?
o What type of measurements or observations will you need to record during your investigation?
To determine how you will collect the data, think about the following questions:
o How often will you collect data and when will you do it?
o How will you make sure that your data are of high quality (i.e., how will you reduce error)?
o How will you keep track of the data you collect and how will you organize it?
To determine how you will analyze the data, think about the following questions:
o What type of data table could you create to help make sense of your data?
o What types of calculations will you need to make? (See below)
o What type of graph could you create to help analyze your data?
Calculations
There are three important formulas that we need to use. Formula 1 states the probability of a marble hitting one of the
stationary marbles:
(1)
Probability = Total number of collisions
Total number of rolls
There are several factors affecting the probability of a rolled marble hitting a stationary marble:

There is a direct relationship between the size or diameter (d) of a marble and the probability of a collision. The
larger the marble the greater the probability of a collision.

There is a direct relationship between the number of marbles (n) and the probability of a collision. The more
marbles there are in the target area, the greater the probability of a collision.

There is an indirect relationship between the size of the opening (L) to the target area and the probability of a
collision. The larger the opening, the smaller the probability of a collision since the marbles will be spaced out
more in the target area. If the opening to the target area is smaller, the marbles will be closer together and the
probability of a collision will be greater.
Putting these factors together in an equation, we can restate the probability of 2 marbles colliding:
(2)
Probability = 2 d n
L
We now have two equations for probability. Let’s set them equal to each other:
Probability = 2 d n = Total number of collisions
L
Total number of rolls
Also remember that:
n = number of marble in the target area
L = opening of your wooden frame in cm
d = diameter of the marble
Connections to Crosscutting Concepts
As you work through your investigation, be sure to think about




the importance of identifying patterns;
how system models contribute to understanding science;
the difference between laws and theories in science, and
the importance of imagination and creativity in your investigation.
Initial Argument
Once your group has finished collecting and analyzing your data, you will
need to develop an initial argument. Your argument must include a
claim, which is your answer to the guiding question. Your argument
must also include evidence in support of your claim. The evidence is
your analysis of the data and your interpretation of what the analysis
means. Finally, you must include a justification of the evidence in your
argument. You will therefore need to use a scientific concept or
principle to explain why the evidence that you decided to use is relevant
and important. You will create your initial argument on a whiteboard.
Your whiteboard must include all the information shown in Figure I.E. 1.
FIGURE I.E. 1
Argument presentation on a whiteboard
Argumentation Session
The argumentation session allows all of the groups to share their arguments. One member of each group stays at the
lab station to share that group’s argument, while the other members of the group go to the other lab stations one at a
time to listen to and critique the arguments developed by their classmates. The goal of the argumentation session is not
to convince others that your argument is the best one; rather, the goal is to identify errors or instances of faulty
reasoning in the initial arguments so these mistakes can be fixed. You will therefore need to evaluate the content of the
claim, the quality of the evidence used to support the claim, and the strength of the justification of the evidence
included in each argument that you see. To critique an argument, you might need more information that what is
included on the whiteboard. You might, therefore, need to ask the presenter one or more of the following questions,
such as:
 How did your group collect the data? Why did you use that method?
 What did your group do to make sure the data you collected are reliable? What did you do to decrease
measurement error?
 What did your group do to analyze the data, and why did you decide to do it that way?
 Is that the only way to interpret the results of your group’s analysis? How do you know that your interpretation
of the analysis is appropriate?
 Why did your group decide to present your evidence in that manner?
 What other claims did your group discuss before deciding on that one? Why did you abandon those alternative
ideas?
 How confident are you that your group’s claim is valid? What could you do to increase your confidence?
Once the argumentation session is complete, you will have a chance to meet with your group and revise your original
argument. Your group might need to gather more data or design a way to test one or more alternative claims as part of
this process. Remember, your goal at this stage of the investigation is to develop the most valid or acceptable answer to
the research/guiding question!
Report
Once you have completed your research, you will need to prepare an investigation report that consists of three sections
that provide answers to the following questions:
1. What question were you trying to answer and why?
2. What did you do during your investigation and why did you conduct your investigation in this way?
3. What is your argument?
Your report should answer these questions in four pages or less. The report must be typed and any diagrams, figures, or
tables should be embedded into the document. Be sure to write in a persuasive style; you are trying to convince others
that your claim is acceptable and valid!
Investigation Timeline Option E
Stage 1: Identify the task and the guiding question. Hold a “tool talk”
Day 1
Small groups of students
then…
50 Minutes
Stage 2: Design a method and collect data
Groups then…
Day 2
50 Minutes
Finish Stage 2. Collect data
Groups then…
Stage 3: Analyze data and develop a tentative
argument
Day 3
Each group then shares its argument during an…
Stage 4: Argumentation
session
The teacher then leads an…
50 Minutes
If needed,
groups
can…
Collect additional data or
reanalyze the collected data
The teacher then leads an…
Stage 5: Explicit and reflective discussion
Individual students then…
Day 4
Stage 6: Write and investigation
report
50 Minutes
The report then goes through a …
Day 5
Stage 7: Double-blind group peer
review
Each student then…
Stage 8: Revises and submits his or her
report
50 Minutes
Lab 11: Atomic Structure and Electromagnetic Radiation: What Are the Identities
of the Unknown Powders?
Introduction
FIGURE L11.1
According to our current theory about the structure of
atoms, electrons are found around the nucleus in
regions called orbitals (see Figure L11.1). Orbitals
represent the potential position of an electron at any
given point in time. Orbitals are located at different
distances from the nucleus and have different energy
levels associated with them. Each orbital, however, can
only hold two electrons. The electrons of an atom fill
low-energy orbitals, which are the ones closer to the
nucleus, before they fill higher-energy ones.
Electrons are in a ground state when under
stable conditions. When the electrons in an atom are
bombarded with energy from an outside source,
however, they absorb that energy and jump
temporarily to a higher energy level. The electrons are
said to be in an excited state when this happens. When
those electrons release that energy, it is emitted in the
electromagnetic radiation. If that electromagnetic
radiation falls between 400 and 700 nanometers (nm)
in wavelength, it is given off in the form of visible light.
Many common metal ions, such as Li+, Na+, K+,
+2
Ca , Ba+2, Sr+2, and Cu+2, produce a distinct color of
visible light when they are heated. These ions emit a
unique color of light because they consist of atoms that
have a unique electron configuration. Chemists can
therefore identify these elements with a flame test. To
conduct a flame test, a clean wire loop or wooden splint
that has been soaked in distilled water is dipped into a
powder of solution and then placed into the hottest
portion of a flame (see Figure L11.2).
The unique color that we observe during a
flame test is actually mixture of several different
wavelengths of visible light. Chemists can use a
spectroscope to identify these various wavelengths.
This technique is known as spectroscopy.
A
spectroscope splits light to form an emission line
spectrum. The emission line spectrum for hydrogen is
provided in Figure L11.3. The emission line spectrum
for hydrogen consists of four different wavelengths of
light (410 nm, 434 nm, 486 nm, and 656 nm). In this
investigation, you will have an opportunity to conduct a
flame test and use a spectroscope to identify four
unknown powders.
Each of the three p orbitals (top row) and all three
together on the same atom (bottom)
FIGURE L11.2
Flame Test
FIGURE L11.3
The hydrogen emission spectrum with wavelength labels
form of
Your Task
Use a flame test and spectroscope to determine the emission line spectrum of six different powders. Then determine
the identity of four unknown powders using a flame test, a spectroscope, and the emission line spectra from the six
known powders.
The guiding question of this investigation is, What are the identities of the unknown powders?
Materials
You may use any of the following materials during your investigation:
Consumables







Equipment
Calcium chloride, CaCl2
Copper (II) chloride, CuCl2
Lithium chloride, LiCl
Potassium chloride, KCl
Sodium chloride, NaCl
Strontium chloride, SrCl2
4 unknown powders




Beakers
Bunsen burner
Wooden splints
Spectroscope
Safety Precautions
Follow all normal lab safety rules. Your teacher will explain relevant and important information about working with the
chemicals associated with this investigation. In addition, take the following safety precautions:
 Wear indirectly vented chemical-splash goggles
 Use caution when working with Bunsen burners. They can burn skin, and combustibles and flammables must be
kept away from the open flame.
 If you have long hair, tie it back behind your head.
 Handle all glassware with care.
 Wash your hands with soap and water before leaving the laboratory.
Investigation Proposal Required?
 Yes
 No
Getting Started
To answer the guiding question, you will need to design and conduct an investigation. To accomplish this task, you must
determine what type of data you need to collect, how you will collect the data, and how you will analyze the data.
To determine what type of data you need to collect, think about the following questions:
o How will you be able to identify a substance based on a flame test?
o What type of measurements or observations will you need to record during your investigation?
To determine how you will collect the data, think about the following questions:
o How often will you collect data and when will you do it?
o How will you make sure that your data are of high quality (i.e., how will you reduce error)?
o How will you keep track of the data you collect and how will you organize it?
To determine how you will analyze the data, think about the following questions:
o What type of data table could you create to help make sense of your data?
o What types of calculations will you need to make?
Connections to Crosscutting Concepts
As you work through your investigation, be sure to think about




the importance of identifying patterns;
how system models contribute to understanding science;
the difference between laws and theories in science, and
the importance of imagination and creativity in your investigation.
Initial Argument
Once your group has finished collecting and analyzing your data, you will
need to develop an initial argument. Your argument must include a claim,
which is your answer to the guiding question. Your argument must also
include evidence in support of your claim. The evidence is your analysis of
the data and your interpretation of what the analysis means. Finally, you
must include a justification of the evidence in your argument. You will
therefore need to use a scientific concept or principle to explain why the
evidence that you decided to use is relevant and important. You will create
your initial argument on a whiteboard. Your whiteboard must include all
the information shown in Figure L11.4.
FIGURE L11.4
Argument presentation on a whiteboard
Argumentation Session
The argumentation session allows all of the groups to share their
arguments. One member of each group stays at the lab station to share that group’s argument, while the other
members of the group go to the other lab stations one at a time to listen to and critique the arguments developed by
their classmates. The goal of the argumentation session is not to convince others that your argument is the best one;
rather, the goal is to identify errors or instances of faulty reasoning in the initial arguments so these mistakes can be
fixed. You will therefore need to evaluate the content of the claim, the quality of the evidence used to support the
claim, and the strength of the justification of the evidence included in each argument that you see. To critique an
argument, you might need more information that what is included on the whiteboard. You might, therefore, need to
ask the presenter one or more of the following questions, such as:
 How did your group collect the data? Why did you use that method?
 What did your group do to make sure the data you collected are reliable? What did you do to decrease
measurement error?
 What did your group do to analyze the data, and why did you decide to do it that way?
 Is that the only way to interpret the results of your group’s analysis? How do you know that your interpretation
of the analysis is appropriate?
 Why did your group decide to present your evidence in that manner?
 What other claims did your group discuss before deciding on that one? Why did you abandon those alternative
ideas?
 How confident are you that your group’s claim is valid? What could you do to increase your confidence?
Once the argumentation session is complete, you will have a chance to meet with your group and revise your original
argument. Your group might need to gather more data or design a way to test one or more alternative claims as part of
this process. Remember, your goal at this stage of the investigation is to develop the most valid or acceptable answer to
the research/guiding question!
Report
Once you have completed your research, you will need to prepare an investigation report that consists of three sections
that provide answers to the following questions:
1. What question were you trying to answer and why?
2. What did you do during your investigation and why did you conduct your investigation in this way?
3. What is your argument?
Your report should answer these questions in four pages or less. The report must be typed and any diagrams, figures, or
tables should be embedded into the document. Be sure to write in a persuasive style; you are trying to convince others
that your claim is acceptable and valid!
Investigation Timeline Option D
Stage 1: Identify the task and the guiding question. Hold a “tool talk”
Day 1
Small groups of students then…
50 Minutes
Stage 2: Design a method and collect data
Groups then…
Stage 3: Analyze data and develop a tentative argument
Day 2
Each group then shares its argument during an…
Stage 4: Argumentation session
The teacher then leads an…
50 Minutes
If needed,
groups can…
Collect additional data or
reanalyze the collected data
The teacher then leads an…
Stage 5: Explicit and reflective discussion
Individual students then…
Homework
Stage 6: Write and investigation report
The report then goes through a …
Day 3
30 Minutes
Stage 7: Double-blind group peer review
Each student then…
Homework
Stage 8: Revises and submits his or her report