Chemistry 110
Exam 1, 8:00 Section
G. E. Rodgers
(There are 140 points on this exam.)
September 26, 2003
Name _________________________________
Honor code: ____________________________
(30 pts) I. Multiple-Multiple Choice: Circle the letters or letters corresponding to all the correct
answers.
1. The team with the overall best offensive statistics in major league baseball is the
(a) Boston Red Sox*
(b) New York Yankees
(c) Atlanta Braves (d) San Francisco Giants
2. A bathroom floor measuring 76 by 56 inches would require approximately how many
square feet of floor tiling?
(a) 4300
(b) 480
(c) 350
(d) 39
(e) 30
(f) none of these
3. The percent error between the experimentally determined wavelength, 441 nm, and the
accepted value, 436 nm, is
(a) 1.1468
(b) 1.147
(c) 1.15
(d) 1.1
(e) 1
(f) none of these
4. The atomic weight of argon is 39.948 amu. Given that there is more than one naturally
occurring isotope of argon, how many argon atoms actually weigh 39.948 amu?
(a) all
(b) almost all
(c) probably about half
(d) practically none
(e) none
5. The 46Sc3+ cation would contain
(a) 3 protons
(b) 21 protons
(c) 25 protons
(d) 25 nucleons
(e) 25 neutrons
(f) 18 electrons
(g) 21 electrons
(h) 24 electrons
6. Of the following sets of four quantum numbers (n, l, ml, ms), identify the ones that cannot
exist for an electron in an atom.
(a) 2, 2, -1, +½
(b) 6, 0, 0, +½
(c) 5, 4, +5, +½
(d) 4, -1, 0, -½
7. In an oil drop experiment carried out in another universe far, far, away, the charges on the
oil drops are 1.50, 2.25, 3.375, and 7.50 Siskos (S). The fundamental charge of electricity is,
according to this limited data,
(a) 0.375S
(b) 0.750S
(c) 1.50S
(d) 2.25S
(e) none of these
* This is the correct answer. The Boston Red Sox currently lead the major leagues in batting
average, on base percentage, slugging average, RBIs, runs, hits, walks, and doubles; they lead
the American League in home runs.
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8. The number of subshells possible for n = 5 is
(a) 2
(b) 3
(c) 4
(d) 5
(e) 6
(f) 9
(g) 16
(h) 25
9. The radial distribution function is the probability of finding an electron
(a) on a radial line as one moves from the nucleus outwards.
(b) within a boundary surface surrounding the nucleus.
(c) on a series of concentric spheres of radius r moving out from the nucleus.
(d) on a series of concentric circles of radius r moving out from the nucleus.
(e) none of these
II. A Few Problems
(9 pts) 1. Most of the gamma radiation emitted by the nuclear decay of a technetium-99 atom used in
radiopharmaceuticals has an energy of 140.511 keV. Calculate the frequency (in Hz) of one
photon of this gamma radiation. (1 eV = 1.6022 x 10-19 J; 1 nm = 10-9 m)
(8 pts) 2. (a) Calculate the wavelength (in nm) for the transition from the n = 4 to the n = 2 levels in
the hydrogen atom. (b) In what region of the electromagnetic spectrum do you expect this
wavelength to appear?
(8 pts) 3. Pedro Martinez, the famous Red Sox pitcher who has won three Cy Young Awards and
again this year leads the American League in a number of pitching categories, has reportedly
thrown a fast ball 98 miles per hour. If a baseball weighs 142 grams, what is its de Broglie
wavelength (in meters) when Pedro pitches it? Would this wave motion be a factor in fooling
the batter and making him swing in vain to hit it? Why or why not? (1 km = 0.6214 mile)
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(10 pts) 4. When light with a wavelength of 425 nm falls on a potassium metal surface, an electron is
ejected at a speed of 4.88 x 105 m/s. What energy was expended in removing the electron from
the metal surface? Express the answer in joules (per electron). (mass of electron = 9.109 x
10-31 kg)
(8 pts)
5. Suppose you have data that gives experimental values of the frequency of light versus
wavelength, how could you graphically determine the speed of light? Be specific by showing a
plot with well-labelled axes (with units) and an indication of how the speed of light would be
determined from the plot.
III. Explanations and Short Answer
(12 pts) 1. The Mass Spectrometer. Briefly criticize the following statement: +2 ions are deflected
more in a mass spectrometer than +1 ions. As part of your answer, draw a schematic diagram
of a mass spectrometer and briefly explain how it works.
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(15 pts) 2. The Nature of Atomic Orbitals. Using the concept of the wave-particle duality of matter,
describe as clearly as possible what 2s and 2p atomic orbitals are. In as much detail as time
allows, explain why the 2s orbital is of lower energy than the 2p orbital in a many-electron atom
(MEA) but these two orbitals are degenerate in a hydrogen-like species. Draw and refer to
radial distribution functions (and/or dot density diagrams ), effective nuclear charge, and
Coulomb potential energy as part of your answer. Label your radial distribution functions
clearly.
(8 pts) 3. Energy Levels in the Modern Atom. Briefly describe how Erwin Schrödinger explained
what was happening in an atom to cause the highest wavelength emission line of the Balmer
series of the hydrogen atom. Be as detailed and specific as time allows.
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IV. Electronic Configurations – in this Universe and Others.
(8 pts)
1. Write the full ground-state electron configuration and the abbreviated orbital diagram (or
abbreviated “box diagram”) of the bromine (Z = 35) atom.
(6 pts)
2. Write a full set of quantum numbers for the electron gained when a bromine atom takes on
an electron to become the Br1- ion.
(9 pts)
3. Suppose you are in a “Spock Universe” in which there are three allowed values of the spin
quantum number, ms. Write the electron configuration for bromine under those circumstances.
What type of element (name a section of the periodic table) would bromine be under these
circumstances? Briefly justify your answer.
(9 pts)
4. Suppose you now travel to a “Spock Universe” in which the l orbital quantum number can
be as high as n in each case (but the spin quantum number is either ±½ as it is in our universe).
That is, if l = 0, 1, . . . n, how would this affect the electron configuration of bromine? Write
the electron configuration under these new circumstances. (Assume that all the other quantum
numbers are the same as in our universe.) Now what type of element would bromine be?
Briefly justify your answer.