A Journey of Student Understanding
in General Chemistry
Or understanding how students
learn chemistry
Alexander Grushow
Associate Professor (and Chair)
Chemistry, Biochemistry & Physics
grushow@rider.edu
General Chemistry
• CHE 120 is a pre-requisite for second
semester general chemistry (and organic
chemistry)
• Taken by almost all science majors
• About half are freshman
• Most will not be Chemistry or Biochemistry
majors
Dread of a Chemistry Class
•
•
•
•
Lots of information
Lots of problems to do
Lots of formulas to remember
Lots of information to assimilate
• Mechanism to assess achievement is to see
if students can do a problem based on any
of the above
Periodic Trends
IA
VIIIA
1
H
2
1.0079
IIA
IIIA
IVA
VA
3
4
5
6
7
Li Be
B
6.941 9.0122
11
22.990 24.305
19
20
N
8
O
9
F
4.0026
10
Ne
10.811 12.011 14.007 15.999 18.998 20.180
12
Na Mg
C
VIA VIIA
He
13
VIIIB
IIIB
IVB
VB
VIB VIIB
21
22
23
24
K Ca Sc Ti
25
26
27
28
IB
IIB
29
30
14
Al Si
15
P
16
S
17
18
Cl Ar
26.982 28.086 30.974 32.066 35.453 39.948
31
32
33
34
35
36
V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
• How does atomic
size change as you go
L-R in a row?
39.098 40.078 44.956 47.88 50.942 51.996 54.938 55.847 58.933 58.693 63.546 65.39 69.723 72.61 74.922 78.96 79.904 83.80
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
85.468
87.62
88.906
91.224
92.906
95.94
(99)
101.07
102.91
106.42
107.87
112.41
114.82
118.71
121.76
127.60
126.90
131.29
55
56
57
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
132.91
137.33
138.91
178.49
180.95
183.85
186.21
190.2
192.22
195.08
196.97
200.59
204.38
207.2
208.98
(210)
(210)
(222)
87
88
89
104
105
106
107
108
109
(223)
(226)
(227)
(261)
(262)
(263)
(262)
(265)
(266)
58
59
60
61
62
63
64
65
66
67
68
69
70
71
Rb Sr
Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te
Cs Ba *La Hf Ta W Re Os Ir
I
54
Xe
Pt Au Hg Tl Pb Bi Po At Rn
Fr Ra Ac Rf Db Sg Bh Hs Mt
* Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Tb Lu
140.12 140.91 144.24 (147) 150.36 151.97 157.25 158.93 162.50 164.93 167.26 168.93 173.04 174.97
90
91
92
93
94
95
96
97
98
99
(249)
(252)
(252)
1 00
1 01
1 02
1 03
(259)
(262)
Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr
232.04 231.04 238.03 (237)
(239)
(241) (244)
(257) (258)
• How does atomic
size change as you go
down a column?
A Change in Teaching Strategy (1998)
• Began using inquiry-based techniques in the
classroom.
• Students use data and a specially developed
line of questioning to develop conceptual
understanding.
• Students (should) learn how to apply
concepts to develop new knowledge and
answer questions.
Surface Learning
vs.
Deeper Understanding
• How do I assess this?
– Not drill & kill
– Not basic recall
– Not even general solution answers to “typical”
problems
• Need a different assessment mechanism
BRIDGE provided:
• Discussions of teaching strategies
• Forum for understanding student learning
behaviors
• Methods for classroom evaluation
• Assessment of student understanding
Layered and connected assessments
Assertion - Reason questions
Na+ is a smaller ion than Br–.
BECAUSE
The first ionization energy for a Na atom will be larger than that of a Br atom.
a) True, false
****
b) False, true
c) False, false
d) True, true
e) True, true and correct explanation
Layered and connected assessments
(version 2)
Assertion - Reason questions
Na+ is a smaller ion than Br–.
BECAUSE
The first ionization energy for a Na atom will be smaller than that of a Br atom.
a) True, false
b) False, true
c) False, false
d) True, true
****
e) True, true and correct explanation
Layered and connected assessments
(version 3)
Assertion - Reason questions
Na+ is a smaller ion than Br–.
BECAUSE
The valence electrons in Br occupy a shell that is further from the nucleus than the
valence electrons in Na.
a) True, false
b) False, true
c) False, false
d) True, true
e) True, true and correct explanation
****
Layered and connected assessments
(another example)
Assertion - Reason questions
In a closed gaseous system at constant volume, an increase in temperature leads to an
increase in pressure.
BECAUSE
At higher temperatures gas molecules hit the container wall more often.
a) True, false
b) False, true
c) False, false
d) True, true
e) True, true and correct explanation
Deeper explanations
Completely answer two of the following four – in the spaces given.
a) The sugar sucrose (C12H22O11) readily dissolves in water, yet it is not an ionic molecule.
Explain how this happens.
b) Why do you feel cold when you step out of the shower or the swimming pool before you
dry yourself off?
c) Why does water boil at a lower temperature in the Rocky Mountains?
d) Cooking grease does not dissolve in water. How does soap serve to make grease soluble
in water?
Lessons
• Don’t swing the pendulum too far in one
direction.
• Some students can only do recall problems,
however this is also an important skill.
• It takes longer to develop or score an
assessment for deeper learning.
Questions?
http://www.rider.edu/~bridge
Alex Grushow: grushow@rider.edu