Hour Exam I
Fall 2011
Name:
10-6-2011
1) An electron in a plasma TV display screen is moving freely at a velocity of 5000
m/s. What is its kinetic energy in Joules?
a) 2.2.10-18
b) 3.3.10-30
c) 4.1.10-20 d) 2.2.10-23
✔e) 1.1.10-23
Who says beans don’t have an immune system? Identify the numbered hybridized
atoms in wyerone acid, which beans use to kill attacking fungus.
2) ✔a) sp
b) sp2
c) sp3
3) a) sp
b) sp2
✔c) sp3
4) a) sp
✔b) sp2
c) sp3
5) The degeneracy of the first excited state of a particle in a cubic box of either
one, two or three dimensions is: [Hint: cubic means all lengths L are equal.]
✔a) 1, 2, 3
b) 1, 1, 1
c) 0, 0, 0
d) 1, 2, 2
e) 3, 3, 3
6) What is the longest wavelength of a photon that will still ionize a Lithium atom?
a) 15.7 nm
b) 157 nm
c) 0.004 m
✔d) 230 nm
e) 400 nm
7) Which of the following is the x-p plot for the lowest energy state of a spring
allowed by the Heisenberg principle? ✔d
8) The Balmer series of a hydrogen atom is a series of sharp emission lines that
ends in the n=2 state. The longest wavelength line is called Balmer-. What color
is this line? [Hint: emitted color is the same as absorbed color.]
a) UV
b) blue-green
c) yellow
1
✔d) red
e) IR=infrared
Hour Exam I
Fall 2011
Name:
10-6-2011
9) What is the effective nuclear charge of magnesium and, given the IP of similar
atoms on the hint page, what is its ionization potential in kJ/mole?
a) 1, 942
✔b) 1.5, 738
c) 1.5, 942
✔d) 2, 738
e) 2, 942
Note: Depending on how you calculate Zeff, both 1.5 and 2 are acceptable
10) A 4p orbital (n=4, ℓ=1) has how many nodes? (planar = angular is a “flat”
node, radial is a “spherical” node)
a) 1 radial, 2 planar
d) 2 radial
b) 3 radial, 1 planar
✔e) 2 radial, 1 planar
c) 1 radial, 1 planar
11) What is the valence e- configuration of iron, the most stable nucleus in the
universe?
a) 4s23d7
b) 4s13d7
✔c) 4s23d6 d) 3s23d7
e) 3s13d7
12) Two methyl radicals are coming together to make a chemical
bond and form ethane. The potential energy as a function of the
C to C bond distance looks like ✔c
V()
a)
V()
V()
b)
0
R
c)
R
0
V()
d)
R
0
0
R
13) Based on electronegativities, which of the following uncharged molecules has
incorrectly assigned partial charge(s) ?
✔b
+ /2
+/2 - + /2
- H
a) O
b)
O=S=O
H
+ /2
+
+ c) I-Br
2
- F

F
d) F-S-F -F F -
e) a and d
Hour Exam I
Fall 2011
Name:
10-6-2011
14) Using MO theory, the bond order and magnetism of the charged molecule
ArH+, common in the upper atmosphere of the Earth, is
a) 1, paramagnetic
b) 0.5, diamagnetic
c) 0.5, paramagnetic
✔d) 1, diamagnetic
e) 1.5, paramagnetic
The MO diagram for ArH+ would
probably be similar to that of HCl, if we
assume that H and Ar+ is combining.
15) When you fill electrons into the MO diagram of the N 2 molecule, the lowest
unoccupied MO looks like:
✔a)
b)
c)
d)
e)
16) Ozone is a dangerous pollutant at low altitude, but an important UV screen in
the upper atmosphere. Which Lewis dot structure is closest to the actual
wavefunction of Ozone? ✔b
17) Phosphene (PH3) is a toxic gas used in the manufacture of n-doped
semiconductors chips. All H-P-H bond angles are 93°. To a first approximation,
which atomic/hybrid orbitals on phosphorous best describe the bonding in the
localized electron picture?
✔a
3
Hour Exam I
Fall 2011
Name:
pz
a)
py
px
10-6-2011
sp3
pz
b) sp2
sp2
c)
sp3
sp3
pz
d)
sp
sp
sp3
sp2
pz
py
e) sp2
sp2
sp2
18) Two electrons fill into energy levels as shown to make the
lowest energy state. Which of the following is definitely true:
E
E
a) This must be an excited state, could never be the lowest state
b) This is close to the lowest energy state, but the upper e- should be flipped
✔c) If E is small, Pauli exclusion minimizes e- repulsion, making it the lowest state
d) This violates the Pauli exclusion principle because both e- have the same spin
e) If E is large, the upper e- should be moved down without flipping.
19) What is the electron affinity of O+ atomic ion?
a) 1402
✔b) 1314
d) The same as O atom
c) 1682
e) insufficient information on hint page
20) px ~ sinθ cosφ. py ~ sinθ sinφ. pz ~ cos θ. An electron is in the triply
degenerate p state, nothing further specified. The probability P(θ, φ) of finding the
electron at angles θ and φ is
a) sinθ (sinφ + cosφ)
d) independent of θ
b) independent of φ
e) sin2θ sinφ cosφ
✔c) independent of θ and φ
21) A single potassium atom is inside the cavity of a C60 molecule (cavity diameter
7 Å) in the lowest possible energy state. What is the velocity spread?
a) 0
✔b) 15 m/s c) 1500 m/s
d) ª
1
15
c
e) K does not fit inside a C60 cavity
22) Which particle has greater momentum?
a) An electron moving at 5000 m/s
✔b) An X-ray photon of 0.5 nm wavelength
(And yes, because a photon has momentum, it can ‘kick’ an electron around
when they ‘collide’, and vice-versa.)
4
Hour Exam I
Fall 2011
Name:
10-6-2011
23) The molecule trans-hexatriene =
acts as a box for electrons
because of the conjugated pi electrons. Assuming the particle in a box model for
the pi electrons, and knowing the lowest energy photon that can be absorbed has
frequency 1.2.1015 Hz, you estimate the size of the hexatriene ‘box’ to be:
a) < 2 Å
b) 2 to 4 Å
✔d) 6 to 8 Å
c) 4 to 6 Å
e) >8 Å
24) Which of the following orbitals do not have the right symmetry to make a
bonding or antibonding combination when the orbitals are brought together along
the dotted line?
✔d
a)
b)
c)
d)
e)
25)



1)
2)
x
x
x


4)
3)
x
5)
x
Which wavefunction above best matches the orbital formula ~ (2-r/a) e-r/a?
a) 4, 2s
b) 2, 1s
✔c) 5, 2s
d) 3, 3px
e) 1, 3px
That’s it, folks!
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