SCH 3U
Trends in the Periodic Table: Graphing Assignment
Introduction: In this assignment you will construct three different graphs to obtain a visual
representation of the changes in three properties of elements as their atomic number increases. By
completing this activity, you should see that elements are grouped on the periodic table according to
similarities in these properties. The three properties you will investigate are: Atomic radius,
ionization energy, and electronegativity.
Materials: Data for first 20 elements (below)
3 sheets of graph paper
Procedure:
1) Turn the graph paper sideways so that the long side becomes the x-axis. The x-axis will
represent the atomic number for all three graphs. Spread out values so they fill the length of
the x-axis.
2) Label the y-axis with the given property and establish a scale that begins with ‘0’.
3) Graph the data provided.
4) Label each point with the corresponding element symbol.
5) Between elements 2 and 3, 10 and 11, 18 and 19, draw a red vertical line to separate the four
PERIODS of elements. Label the sections 1 – 4.
6) In each section (1 – 4), draw a curve of best fit among the points (Don’t play connect the dots!)
7) Be sure all axes are labeled (title and units) and each graph has a descriptive title.
Data: See page 2
Follow-Up Questions: Please answer with complete sentences
Atomic radius
1) According to the graph, what happens to the radius (size) of an atom as you move across a
period (row) of the periodic table?
2) According to the graph, what happens to the radius (size) of an atom as you move down a
group (column) of the periodic table?
Ionization Energy
1) Generally, what happens to the ionization energy of an atom as you move across a period of
the periodic table?
2) Generally, what happens to the ionization energy of an atom as you move down a column of
the periodic table?
3) How do these trends differ from atomic radius?
Electronegativity
1) Generally, what happens to the electronegativity of an atom as you move across a period?
2) Generally, what happens to the electronegativity of an atom as you move down a column?
3) How are these trends differ from atomic radius?
Trends in the Periodic Table: Graphing Assignment
Data Tables:
Table 1: Atomic Number and Atomic Radius for elements 1 – 20
Atomic Number
Atomic Radius (pm)
Atomic Number
1
37
11
2
32
12
3
152
13
4
111
14
5
79
15
6
77
16
7
74
17
8
76
18
9
71
19
10
69
20
Atomic Radius (pm)
186
160
143
117
110
102
100
97
227
197
Table 2: Atomic Number and Ionization Energy for elements 1 – 20
Atomic Number
Ionization Energy (kJ)
Atomic Number
1
1294
11
2
2336
12
3
511
13
4
886
14
5
787
15
6
1071
16
7
1380
17
8
1294
18
9
1656
19
10
2048
20
Ionization Energy (kJ)
486
725
569
775
1046
985
1236
1496
408
581
Table 3: Atomic Number and Electronegativity for elements 1 - 20
Atomic Number
Electronegativity
Atomic Number
1
2.1
11
2
No Value
12
3
1.0
13
4
1.5
14
5
2.0
15
6
2.5
16
7
3.0
17
8
3.5
18
9
4.0
19
10
No Value
20
Electronegativity
0.9
1.2
1.5
1.8
2.1
2.5
3.0
No Value
0.8
1.0