NAME:____________________________
Fall 2016
INSTRUCTIONS:
Student Number:______________________
Chemistry 1000 Midterm #1B
____/ 70 marks
1) Please read over the test carefully before beginning. You should have
8 pages of questions and a formula/periodic table sheet.
2) If your work is not legible, it will be given a mark of zero.
3) Marks will be deducted for incorrect information added to an
otherwise correct answer.
4) Marks will be deducted for improper use of significant figures and for
missing or incorrect units.
5) Show your work for all calculations. Answers without supporting
calculations will not be given full credit.
6) You may use a calculator.
7) You have 90 minutes to complete this test.
Confidentiality Agreement:
I agree not to discuss (or in any other way divulge) the contents of this exam until after 5:00pm
Mountain Time on Tuesday, October 18th, 2016. I understand that breaking this agreement
would constitute academic misconduct, a serious offense with serious consequences. The
minimum punishment would be a mark of 0/70 on this exam and removal of the “overwrite
midterm mark with final exam mark” option for my grade in this course; the maximum
punishment would include expulsion from this university.
Signature: ___________________________
Course: CHEM 1000 (General Chemistry I)
Semester: Fall 2016
The University of Lethbridge
Date: _____________________________
Question Breakdown
Spelling matters!
Fluorine = F
Flourine =
Fluorene = C13H10
Q1
Q2
Q3
Q4
Q5
Q6
Q7
Q8
Q9
Q10
Q11
Q12
Q13
/ 15
/2
/6
/5
/7
/5
/3
/2
/2
/8
/5
/4
/6
Total
/ 70
NAME:____________________________
1.
Student Number:______________________
Fill in each blank with the word or short phrase that best completes the sentence.
[15 marks]
(a)
I has one stable isotope. Its atomic number is _____ and its mass number is _____.
(b)
88
(c)
A(n) __________________________ is the antimatter equivalent of an electron.
(d)
A reaction in which two smaller nuclei combine to give one large nucleus would be
Ge is an unstable nuclide expected to undergo a(n) ______________________ reaction.
classified as a(n) _____________________ reaction.
(e)
When a person’s exposure to radiation is reported in Sieverts, the property being reported
is the ____________________________________________.
(f)
Both electrons and light have a “dual nature”. They behave as both ________________
and ___________________________.
(g)
Hydrogen is the only neutral element for which the atomic energy levels can be easily
calculated because ________________________________________________________.
(h)
The principle which states that no two electrons in an atom can share the exact same set
of quantum numbers is the _________________________________________________.
(i)
Due to Heisenberg’s Uncertainty Principle, we cannot know the exact values for the
___________________ and _______________________ of an electron at the same time.
(j)
The ion most commonly formed from S has a charge of _____.
(k)
A neutral atom of Ca has _____ core electrons and _____ valence electrons.
2.
N 
Briefly demonstrate how the formula ln (2 ) = k ⋅ t1 / 2 is derived from ln 2  = −k (t 2 − t1 ) .
 N1 
Your logic must be clear (which may require you to define terms).
[2 marks]
NAME:____________________________
Student Number:______________________
3.
Balance the following nuclear reactions.
Note that you will need to infer some products.
[6 marks]
(a)
63
(b)
55
(c)
2
4.
Rhenium (Re) has two naturally occurring isotopes. The natural abundance of the major
isotope is 62.60%, and the mass of an atom of this isotope is 186.955 750 u. [5 marks]
(a)
Calculate the natural abundance of the minor isotope of rhenium.
[1 mark]
(b)
Calculate the mass of an atom of the minor isotope of rhenium.
[3 marks]
(c)
Identify the two naturally occurring isotopes of rhenium.
[1 mark]
Ni undergoes beta decay.
Fe undergoes electron capture.
H and 6Li react to give 7Be and one other product.
Your answer should be two symbols, each in the format ##Re.
NAME:____________________________
Student Number:______________________
5.
The most abundant isotope of uranium is 238U. It is an alpha emitter.
[7 marks]
(a)
Write a balanced equation for the decay of 238U.
[2 marks]
(b)
Do you expect the energy change for this process to have a positive or negative value?
Why?
[1 mark]
The mark is for the explanation.
(c)
Calculate the energy change for this process. Report your answer in J/mol.
[4 marks]
NAME:____________________________
6.
Student Number:______________________
The Mars Rover Opportunity was launched on July 7th 2003 and is still operational on the
surface of Mars today. It is equipped with an Alpha Particle X-ray Spectrometer (APXS)
device that is used to analyze the chemical composition of the rocks and soil on the
planet. The APXS uses the transuranium element curium, specifically the isotope 244Cm
(α emitter with a half-life of 18.1 years), to produce the alpha particles used in the
analyses. At the time of launch, the source had an activity of 1.11 x 10−6 Bq.
On the anniversary of its launch in 2013, what was the residual activity of the source in
the APXS of Opportunity?
[5 marks]
NAME:____________________________
Student Number:______________________
7.
Calculate the energy required to remove (ionize) the last electron from a Li2+ ion.
[3 marks]
8.
Write the ground state electron configuration for each of the following atoms or ions.
Do not use the noble gas abbreviation.
[2 marks]
(a)
Mg
(b)
Mg2+
9.
Write the ground state electron configuration for each of the following atoms or ions.
Use the noble gas abbreviation.
[2 marks]
(a)
At
(b)
At –
NAME:____________________________
Student Number:______________________
10.
Gadolinium (Gd), a non-radioactive lanthanide element, has a ground state electron
configuration of [Xe] 6s24f 75d1.
[8 marks]
(a)
Briefly comment on any unusual feature of this electron configuration.
(b)
Gd3+ ions (which are attached to suitable carrier drug molecules) are used in Magnetic
Resonance Imaging (MRI) as a magnetic contrast agent.
Write the ground state electron configuration for Gd3+ using the noble gas abbreviation.
[1 mark]
(c)
Provide a valid set of quantum numbers for each of the valence electrons in a Gd3+ ion by
completing the table below. Note that none of the electrons in [Xe] are considered to be
valence electrons for this ion.
[4 marks]
[1 mark]
Not all rows in this table need necessarily be used.
electron #
1
n
l
ml
ms
2
etc.
(c)
What is the criterion for an atom or ion to be considered paramagnetic?
[1 mark]
(d)
Do you predict Gd3+ to be paramagnetic, or not? Explain briefly.
[1 mark]
NAME:____________________________
Student Number:______________________
11.
[5 marks]
(a)
Draw each of the following atomic orbitals.
[4 marks]
Each orbital must be drawn on a labeled set of axes and must show relative phase.
(i)
(ii)
3 px
3d x 2 − y 2
(b)
How does a 3d x 2 − y 2 orbital differ from the 4d x 2 − y 2 orbital in the same atom?
12.
The following “orbital occupancy diagram” for a ground state atom of beryllium (Be) has
many things wrong with it.
[4 marks]
1s
2s
[1 mark]
2p
(a)
Identify three things that are wrong with the above diagram.
[3 marks]
(b)
Draw a correct orbital occupancy diagram for a ground state atom of Be.
[1 mark]
NAME:____________________________
13.
Student Number:______________________
The threshold frequency of potassium metal is 5.5 ×1014 Hz.
[6 marks]
No credit will be given for answers without supporting calculations.
(a)
If potassium metal in a photocell is irradiated with light with a wavelength of 500. nm,
what will happen? Justify your answer.
[3 marks]
(b)
If potassium metal in a photocell is irradiated with light with a wavelength of 750. nm,
what will happen? Justify your answer.
[3 marks]
NAME:____________________________
Student Number:______________________
Some Useful Constants and Formulae
Fundamental Constants and Conversion Factors
Atomic mass unit (u)
1.660 539 × 10-27 kg
Avogadro's number
6.022 141 × 1023 mol–1
Bohr radius (a 0 )
5.291 772 × 10-11 m
Electron charge (e)
1.602 177 × 10-19 C
Electron mass
5.485 799 × 10-4 u
Planck's constant
Proton mass
Neutron mass
Rydberg Constant (R H )
Speed of light in vacuum
6.626 070 × 10-34 J·Hz-1
1.007 277 u
1.008 665 u
2.179 872 x 10-18 J
2.997 925 x 108 m·s-1
Formulae
E = hν
c = νλ
rn = a0
n2
Z
E n = − RH
A=−
∆E = ∆mc 2
1
λ=
p = mv
Z2
n2
Ek =
∆N
∆t
1 2
mv
2
h
p
M =
∆x ⋅ ∆p >
m
m
or U =
n
n
N 
ln 2  = −k (t 2 − t1 )
 N1 
A = kN
h
4π
ln (2 ) = k ⋅ t1 / 2
Chem 1000 Standard Periodic Table
18
1.0079
4.0026
H
He
1
6.941
2
13
14
15
16
17
2
9.0122
10.811
12.011
14.0067
15.9994
18.9984
Li
Be
B
C
N
O
F
Ne
3
22.9898
4
24.3050
5
26.9815
6
28.0855
7
30.9738
8
32.066
9
35.4527
10
39.948
Na
Mg
11
39.0983
12
40.078
44.9559
K
Ca
Sc
Ti
21
88.9059
22
91.224
23
92.9064
19
85.4678
20
87.62
Rb
Sr
37
132.905
38
137.327
Cs
55
(223)
Fr
87
Ba
3
Y
39
La-Lu
56
226.025
Ra
Ac-Lr
88
4
47.88
Si
P
S
Cl
6
7
8
9
10
11
12
50.9415
51.9961
54.9380
55.847
58.9332
58.693
63.546
65.39
V
Cr
Mn
Fe
Co
Ni
Cu
Zn
Ga
Ge
As
Se
Br
Kr
26
101.07
27
102.906
28
106.42
29
107.868
30
112.411
31
114.82
32
118.710
33
121.757
34
127.60
35
126.905
36
131.29
24
95.94
25
(98)
Zr
Nb
Mo
Tc
41
180.948
42
183.85
43
186.207
Rh
Pd
Ag
Cd
In
Sn
Sb
45
192.22
46
195.08
47
196.967
48
200.59
49
204.383
50
207.19
51
208.980
Ta
W
Re
Os
Ir
Pt
73
(268)
74
(271)
75
(270)
76
(277)
77
(276)
78
(281)
Bh
15
74.9216
Ru
Hf
Sg
14
72.61
44
190.2
72
(265)
Db
13
69.723
Hs
Mt
Ds
Au
79
(280)
Rg
Hg
80
(285)
Cn
16
78.96
17
79.904
Te
I
Xe
53
(210)
54
(222)
Tl
Pb
Bi
Po
At
81
(284)
82
(289)
83
(288)
84
(293)
85
(294)
Nh
Fl
Mc
Lv
Ts
105
106
107
108
109
110
111
112
113
114
115
116
117
138.906
140.115
140.908
144.24
(145)
150.36
151.965
157.25
158.925
162.50
164.930
167.26
168.934
173.04
174.967
La
Ce
Pr
Nd
Pm
Sm
Eu
Gd
Tb
Dy
Ho
Er
Tm
Yb
57
227.028
58
232.038
59
231.036
60
238.029
61
237.048
65
(247)
66
(251)
Ac
Th
90
Pa
91
U
92
Np
93
62
(240)
Pu
94
63
(243)
Am
95
64
(247)
Cm
96
Bk
97
Cf
98
67
(252)
Es
99
68
(257)
Fm
100
69
(258)
Md
101
18
83.80
52
(210)
104
89
Ar
5
40
178.49
Rf
Al
20.1797
70
(259)
No
102
Rn
86
(294)
Og
118
Lu
71
(262)
Lr
103
Developed by Prof. R. T. Boeré (updated 2016)
NAME:____________________________
Some Useful Masses
4
4.001 506 179 u
2α
1
1
1
0
Student Number:______________________
234
90
Th
234.043 601 u
p
1.007 276 467 u
236
90
Th
236.049 657 u
n
1.008 664 916 u
238
91
Pa
238.054 637 u
238
92
U
238.050 788 u
238
93
Np
238.050 947 u
Band of Stability Graph
The graph below shows the band of stability. Stable isotopes are in black. Isotopes that exist but are not stable
are shown in varying shades of gray with the shades of gray corresponding to different half-lives.
The original version of the graph used a rainbow colour scale.
http://commons.wikimedia.org/wiki/File:Isotopes_and_half-life_eo.svg