Name: _________________________________________ Date: ________________ Section: ______________________
UNIT 1: ATOMIC THEORY STUDY GUIDE
Exam Format: 40 minutes
Section Type
10 multiple choice questions
1 free response question (parts a – e)
1 short essay (1 – 3 paragraphs)
Check over your work
Points
10
5
5
N/A
Suggested Time
15 minutes
10 minutes
10 minutes (2 planning, 8 writing)
5 minutes
Vocabulary (including scientists):
 Scientific model
 Atom
 Matter
 Element
 Dalton
 Indivisible model
 Thomson
 Cathode-Ray Tube
Experiment
 Electron










Plum-Pudding Model
Rutherford
Gold Foil Experiment
Alpha particle
Nucleus
Nuclear Model
Bohr
Atomic Emission Spectra
Energy level
Photon
Equations and Constants:
 𝐸𝑝ℎ𝑜𝑡𝑜𝑛 = 𝐸ℎ𝑖 − 𝐸𝑙𝑜𝑤

𝐸𝑛 = −

ℎ = 6.63 𝑥 10−34 𝑘𝑔 •

𝐸𝑝ℎ𝑜𝑡𝑜𝑛 = ℎ𝑣 =
ℎ𝑐
𝜆
What are your scores on each of your exit tickets?
Exit Ticket
Score
𝑍2 𝑅𝐻
𝑛2
𝑚
𝑠
Study Priority









Electronic transition
Double-Slit Experiment
Wave-particle duality
Heisenberg
Uncertainty principle
Electron cloud model
Probability density
Schrodinger
Orbital


𝑅𝐻 = 2.18 𝑥 10−18 𝐽
𝑐 = 3.0 𝑥 108 𝑚/𝑠
Plan
1) For all exit tickets, complete corrections. On a separate sheet of paper, you should number the problem,
write the correct response, and write why you got the problem wrong / how you can study (i.e. “made
algebra error; should complete more practice problems”)
2) Complete the “key points” section for at least the “Purpose of the Unit” section and your lowest two
objectives (you may complete more if you’d like).
3) Complete ALL practice problems for your lowest objective. Complete at least 3 practice problems for the
remaining objectives.
4) OPTIONAL: Create outlines for the “possible essays” to prepare for the short essay question.
KEY POINTS:
The Purpose of the Unit: Analyze how the atomic model has been developed
1) An atom is _________________________________________________________________________________.
2) All matter is made up of ________________.
3) A scientific model is _________________________________________________________________________.
a. Scientific models are supported by experimental _________________________.
b. Models can change over time based on new ____________________________.
c. Models need to be ______________________ and testable: they should be able to predict phenomena
that can be evaluated in a laboratory setting.
4) The majority of this unit was looking at previous models of the atom, the experiments and evidence that
supported those models, and how the model was developed over time by studying the behavior of large groups
of atoms.
1.1a – History of the Atom – Dalton & Thomson
Key Points:
1) ________________________ was the father of Modern Atomic Theory.
a. He proposed that atoms were ____________________________ or could not be broken down.
b. He was the first to suggest that atoms could not be ___________________________________________
in chemical reactions; they were only rearranged.
c. He had two specific pieces of evidence: observing pressure in gases, and identifying that the mass of
reactants = mass of products in chemical reactions.
2) The ___________________________________ model was developed by J. J. Thomson.
a. This was developed based on the _______________________________________ experiment in which
Thomson discovered the __________________________.
b. This discredited Dalton’s belief that atoms were _____________________________.
c. Draw and label a diagram of Thomson’s model:
1.1c – History of the Atom – Rutherford and Bohr
Key Points:
1) The __________________________________ was developed by Ernest Rutherford.
a. This was developed based on the _______________________________________ experiment.
b. In the experiment, Rutherford expected ____________________________________________________
____________________________________________________________________________________.
c. The actual result of Rutherford’s experiment was ____________________________________________
____________________________________________________________________________________.
d. The two main conclusions from Rutherford’s experiment were:
1. __________________________________________________________________________________
2. __________________________________________________________________________________
2) The _______________________________ was developed by Niels Bohr.
a. This solved Rutherford’s problem that he could not explain ____________________________________
____________________________________________________________________________________.
b. Bohr stated that electrons orbit the nucleus at _______________________________.
c. This was developed using the ____________________________________________ of Hydrogen.
1.2 – Atomic Emission Spectra (Analyzing Bohr’s Predictive Model)
Key Points:
1) According to Bohr’s model, Atomic Emission and Absorption Spectra were created when ___________________
transitioned between energy levels, absorbing or emitting ____________________.
2) When an electron moves from a higher energy level to a lower energy level, a photon is ___________________.
3) When an electron moves from a lower energy level to a higher energy level, a photon is ___________________.
4) The energy of a photon emitted or absorbed from an atom is equal to __________________________________.
5) The energies of photons can be measured through frequency or wavelength.
a. Frequency is ____________________ proportional to the energy of a photon.
b. Wavelength is ____________________ proportional to the energy of a photon.
1.3 – The Current Model of the Atom – Heisenberg and Schrodinger
Key Points
1) The _______________________________ experiment showed that photons and electrons exhibit wave-particle
duality.
2) Heisenberg’s Uncertainty Principle states that _________________________________________________
___________________________________________________________________________________.
3) This led to the development of the _____________________________ model of the atom.
4) Schrodinger developed an equation to determine the ________________________ of finding an electron in a
certain location around the nucleus.
5) The volume containing a 90% probability of finding an electron is called an ______________________.
POSSIBLE SHORT ESSAY QUESTIONS
1. Science literacy is the ability for an individual to understand and form opinions on complex scientific ideas. A
common complex scientific idea is often represented by scientific models. Describe what a scientific model is,
how scientific models are developed and changed over time, and why it is important for a global citizen to be
able to use and evaluate scientific models. Be sure to use specific examples either from class or from your own
experiences.
2. In the fourth century B.C.E., the Greek philosopher Democritus described an indivisible particle called “atomos,”
that was the building block of all matter. His idea was discredited by his contemporaries. More than 2000 years
later, English scientist John Dalton made a similar assertion; however, his theory was hailed as visionary. Why
was Dalton’s claim accepted while Democritus’s was not, and how does this paradox still hold true in society? Be
sure to support your assertion using at least two examples from class.
3. When Ernest Rutherford performed his Gold Foil Experiment in the early 1900s, he famously stated, “It was the
most incredible event of my life. It was almost as incredible as if you fired a 15-inch shell at a piece of tissue
paper and it came back and hit you.” How does Rutherford’s quote serve as a paradigm for the development of
atomic theory? Justify your claim using both Rutherford’s experiment and another example from class.
4. Bohr’s shell model was the first atomic model to use mathematics to describe atomic structure, quantitatively
predicting the energies of electrons as they orbited the nucleus. When predicting hydrogen’s emission
spectrum, Bohr observed less than 0.1% difference between his predictions and hydrogen’s emission spectrum.
Despite this, Bohr’s model was a failure. Explain how Bohr’s model failed and describe how the current model of
the atom remedied Bohr’s error. Be sure to use specific evidence from lab and class discussion.
5. Werner Heisenberg, the physicist behind the Uncertainty Principle, once famously stated, “Every experiment
destroys some of the knowledge of the system which was obtained by previous experiments.” What is the
meaning of Heisenberg’s statement? Provide evidence for your assertion from at least two experiments
discussed in class.
6. Niels Bohr once famously stated, “If quantum mechanics hasn't profoundly shocked you, you haven't
understood it yet.” In an ACEITx2 paragraph, support Bohr’s assertion, using at least two examples discussed in
class.
PRACTICE PROBLEMS
1.1a – History of the Atom – Dalton and Thomson
1. Which of the following was NOT a tenant of Dalton’s atomic theory?
A. Atoms have subatomic structure, consisting of a positive nucleus surrounded by electrons
B. The atoms of one element are different from the atoms of another element, but all atoms of the same
element are the identical
C. Atoms cannot be created or destroyed in chemical reactions; they can only be rearranged
D. Atoms can be combined together to form compounds
E. Atoms cannot be broken down into smaller particles
2. Which of the following did J. J. Thomson discover in the cathode-ray tube experiment?
A. The atom
B. The proton
C. The neutron
D. The electron
E. The nucleus
3. Which of the following are made up of atoms?
I.
Elements
II.
Compounds
III.
Matter
A.
B.
C.
D.
E.
I only
I and II only
I and III only
III only
I, II, and III
4. Assess the validity of the following statement: “Dalton’s model of the atom was wrong because he didn’t have
any experimental evidence to support his theory.” Justify your claim.
___________________________________________________________________________________________
___________________________________________________________________________________________
___________________________________________________________________________________________
___________________________________________________________________________________________
5. If Dalton’s model of the atom was correct, what would R.A. Milliken have found about the mass of the negative
particle Thomson observed in his cathode-ray tube experiment?
___________________________________________________________________________________________
___________________________________________________________________________________________
___________________________________________________________________________________________
___________________________________________________________________________________________
1.1c – History of the Atom – Rutherford and Bohr
1. If Thomson’s model of the atom was correct, what would Rutherford have observed in his alpha scattering
experiment?
_____________________________________________________________________________________
_____________________________________________________________________________________
____________________________________________________________________________________
_____________________________________________________________________________________
Use the diagram below to answer the next two questions.
2. In this experiment, most of the alpha particles passed directly through the gold atoms undeflected. What does
this evidence suggest about the structure of the gold atoms?
_____________________________________________________________________________________
_____________________________________________________________________________________
3. In this experiment, about 1% of the alpha particles were deflected at large angles. What does this evidence
suggest about the structure of gold atoms?
_____________________________________________________________________________________
_____________________________________________________________________________________
4. After Rutherford’s gold foil experiment, other scientists looked more closely at the nucleus and discovered it
was made up of smaller, positively charged or neutral particles. Who discovered the neutral particle in the
nucleus of an atom?
A. John Dalton
B. J. J. Thomson
C. Niels Bohr
D. James Chadwick
E. Werner Heisenberg
5. In a flame test, different chemical elements will burn with different colored flames. Niels Bohr asserted that this
was due to atoms emitting photons of different wavelengths. This led Bohr to conclude:
A. Atoms contain photons that orbit the nucleus
B. Photons are quantum particles that exhibit wave-particle duality
C. Electrons are quantum particles that exhibit wave-particle duality
D. Electrons must orbit the nucleus at discrete energy levels
E. Photons must orbit the nucleus at discrete energy levels
1.2 – Atomic Emission Spectra
Use the diagram below to answer the next two questions.
1. What are the the two elements in the unknown spectrum?
A. Li and H
B. Li and He
C. Li and Na
D. H and He
E. H and Na
2. Explain how a bright-line emission spectrum is produced in terms of excited state, energy transitions, and
ground state.
___________________________________________________________________________________________
___________________________________________________________________________________________
___________________________________________________________________________________________
___________________________________________________________________________________________
Use the energy level diagram below to answer the next three questions.
n=3
n=2
n=1
3. Which energy transition will result in the emission of a photon with the greatest wavelength?
A. a
B. b
C. c
D. d
E. e
4. Assuming this diagram illustrates an atom of hydrogen (Z = 1), determine the energy of a photon absorbed when
an electron makes transition e.
5. Determine the frequency of the photon described in question 4.
1.3 – Current Model of the Atom – Heisenberg and Schrodinger
1. Young’s double-slit experiment led to the conclusion that electrons
A. Are negatively charged particles smaller than the atom
B. Orbit the nucleus at discrete energy levels
C. Absorb or emit photons when transitioning between energy levels
D. Exhibit wave-particle duality
E. Are contained within a probability density around the nucleus
2. What is Heisenberg’s Uncertainty Principle?
___________________________________________________________________________________________
___________________________________________________________________________________________
___________________________________________________________________________________________
3. All of the following are true regarding the electron cloud model of the atom EXCEPT?
A. Atoms cannot be created or destroyed in chemical reactions
B. The atom contains a small, dense, positively charged nucleus
C. The electrons of an atom occupy discrete energy levels surrounding the nucleus
D. The location of an electron is given only by a probability density around the nucleus
E. The nucleus is an indivisible fundamental particle of nature
4. Assess the validity of the following statement:
“The electron cloud model of the atom is true because it is supported by experimental evidence, including
how molecules get their shapes. Because of this, the atomic model will never change again.”
___________________________________________________________________________________________
___________________________________________________________________________________________
___________________________________________________________________________________________
___________________________________________________________________________________________
5. In the double slit experiment, if an electron is unobserved going through a slit, the detector will display:
A. An impression
B. A single dot
C. Two straight lines
D. An interference pattern
E. Nothing