CHEM 101 – Exam 1 Study Guide
1 February 2014
Preface
Our first in-class midterm is this Monday. The questions will vary in type, and in many cases draw heavily on
your problem-solving skills. The topics of the questions will be chosen from among the following learning goals
for our study of Chapters 1-3 in Burdge & Overby, Chemistry: Atoms First:
Chapter 3 - The Quantum-Mechanical Model of the Atom
• Understand that light has properties of a wave and a particle
• Quantitatively relate wavelength to frequency and energy to wavelength and frequency
• Understand what it means for energy to be quantized
• Know the size, shapes and orientations of s, p and d orbitals
• Predict how electrons are arranged among the orbitals of an atom
• See the relationship between electron configuration and the periodic table
Chapter 2 - Atoms and the Periodic Table
• Understand the basic composition of an atom and how isotopes differ from one another
• Calculate an average atomic mass
• Understand the basic organization of elements within the periodic table
• Define and understand the concepts of mole and molar mass
• Convert between mass, moles, and numbers of atoms
Chapter 1 - Chemistry: The Science of Change
• Classify and describe matter
• Discuss the uncertainty of a measurement and retain the appropriate number of significant figures through
a calculation
• Properly convert between different types of units
In some cases, these learning goals are fairly specific, in other cases they are more open-ended, and a variety of
questions can arise. However, if you have followed closely each class session, read the chapters actively and
carefully (including study of Worked Examples and the related practice problems, also the section review
questions), completed the online homework, then you have had practice with all the relevant subject material.
There are numerous suggested end-of-chapter questions and problems (shown at the foot of the online lecture
webpages) to provide additional opportunities for checking your understanding, and gaining practice with
problem-solving.
Calculations of de Broglie wavelengths or based on the Uncertainty Principle will not appear on the exam,
although it is a good idea to be familiar with the concepts (as required in answering questions 3.52, 3.62,
background for understanding why electronic energy levels in atoms are quantized). Although there will be
questions relating to quantum numbers, their rules, and writing electron configurations, the preeminent emphasis
will be on the types of questions and problems from the start of the semester up to last Wednesday.
CHEM 101 - Exam 1 Study Guide
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Assumed knowledge: The following prefixes used with SI units: kilo- (k) 103, centi- (c) 10−2, milli- (m) 10−3,
micro (µ) 10−6, nano- (n) 10−9, pico- (p) 10−12. Definitions to know: density and all the terms listed at the end of
the Guide to Success in General Chemistry.
Exam format and sample questions
The exam will consist of somewhere between 12 – 15 questions (3½-4 pages) of various formats: multiple-choice,
true-or-false, problems involving calculations and short-answer questions. See below for the information that will
be provided. The sample questions have appeared on previous exams and are meant to be representative of the
kinds of questions to be expected, not necessarily the distribution of topics that will appear on the actual exam.
Some questions may be quite similar to those below, others may touch on topics not addressed by any of the
samples given.
Potentially useful information:
Physical constants, conversion factors:
Avogadro’s number: NA = 6.022 × 1023
Planck’s constant: h = 6.626 × 10−34 J·s
Speed of light: c = 2.998 × 108 m s−1
Equations:
Coulomb’s law: PEelec � q1q2/r
Relations for EM radiation: c = λν; E = hν
Formula for transitions between energy levels in the hydrogen atom: ∆E = (−2.18 × 10−18 J){(1/nf2) − (1/ni2)}
(You will also have access to the Periodic Table)
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Sample exam questions
1. (8 points) Unit conversions. Make the following conversions
(a) 300 m/s to km/hr
(c) 3.02 × 105 g to kg
(b) 562 nm to m
(d) 10 m3 to L
2. (8 points) (a) For each of the following species, provide a count of the number of protons (p+), neutrons (n), and
electrons (e−).
40
Ar
58
Co
(b) For each of the following, identify the element & isotope by writing its symbol and mass number.
28 p+, 36 n
53 p+, 72 n
3. (8 points) Define and briefly discuss the significance of accuracy and precision in scientific measurement
4. True or false (2 points each; circle one)
(a) When pure water and pure sugar are mixed, the resulting mixture is homogeneous.
T
F
(b) Density is an example of an extensive quantity.
T
F
(c) The difference between 1.3 and 1.0467 has only one significant figure.
T
F
(d) The electron in an energy level nj in the hydrogen atom is in an excited state if j > 0. T
F
(e) 1s22s22p63s13d1 is a possible electron configuration for an excited state of an atom.
F
T
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5. (5 points) What is the volume (in cm3) of 2.5 × 10−2 g of ethylene glycol, which has a density of 1.1132 g/cm3?
6. (3 points) The density of a substance is an example of (circle all that apply):
(a) a chemical property
(b) a physical property
(c) an intensive property
(d) an extensive property
7. (3 points) The rusting of iron illustrates (circle all that apply):
(a) a chemical property
(b) a physical property
(c) an intensive property
(d) an extensive property
8. (7 points) Bromine has two naturally occurring isotopes, Br-79 (atomic mass 78.9183 amu) and Br-81 (80.9163
amu, 49.31% natural abundance). Show how to calculate the average atomic mass for bromine.
9. (12 points) Perform the following:
(a) Calculate the mass (in g) of 1.1 × 1022 gold atoms.
(b) Calculate the number of carbon atoms that are contained in 220 mg of diamond (pure carbon).
(c) Calculate the moles of copper in 3.81 kg of pure copper metal.
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10. (10 points) In the following unlabeled periodic tables, shade in the regions corresponding to:
(a) Main group elements
(d) Transition metals
(b) Non-metals
(e) p-block elements
(c) Alkaline earth metals
(f) d-block elements
11. (18 points) (a) Calculate the wavelength of light emitted from a hydrogen atom in an excited state when an
electron at the n = 4 energy level drops to the n = 2 level. (b) Illustrate the process with an energy level diagram.
(c) Calculate the frequency and energy (in kJ/mol) of the light of wavelength found in (a).
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12. (4 points) What type of orbital do the following shapes represent? (Fill in the boxes with letter designation)
13. (9 points) Write the electron configurations for each of the following
(a) Ne
(b) Si
(c) Cu
14. (8 points) Decribe the difference between an orbit and an orbital, and state why the latter provides a more
satisfactory description of electron distribution within atoms.