SCH3U Matter, Chemical Trends and Bonding
Trends in the Periodic Table
In this exercise, you will construct three different graphs to obtain a pictorial representation of
the changes in three properties of the elements as their atomic number increases. By plotting
these properties, you should see that elements are grouped within the periodic table
according to similarities in these properties. The three properties are atomic radius,
ionization energy, and electronegativity.
Atomic Radius
The atomic radius of an atom is the distance from the centre of the atom to the outermost
shell that contains electrons. A convenient unit for this distance is the picometer, which is
one/one trillionth of a meter (1 x 10-9 m).
Ionization Energy
The ionization energy of an atom is the amount of energy (in kilojoules) that is required to
remove one of the outermost electrons from the atom. In other words, the energy needed to
strip an electron away from the atom.
Electronegativity
The electronegativity of an atom is a measure of the ability of the atom to attract an electron
from another atom. If an atom is really good at ‘stealing’ electrons from another atom, then it
has a high electronegativity value. The Noble Gas elements do not have electronegativity
values since they are stable with full outer energy levels.
Procedure:For each set of data...
1. Turn the graph paper sideways so that the long side becomes the X-axis. The X-axis is
the Atomic Number for all graphs and should take up the whole side of the paper.
2. Label the Y-axis with the given property and establish a scale that begins with ‘0’.
3. Graph the data below.
4. Label each point with the corresponding element symbol.
5. At atomic numbers 2(He), 10(Ne) and 18(Ar) draw a red vertical line through the graph.
This separates the plot into four sections. Label the sections 1 – 4.
6. In each section, connect the points.
7. Include a title.
Atomic Radius for the First 20 Elements
Atomic Number
1
2
3
4
5
6
7
8
9
10
Atomic Radius
(picometers)
37
32
152
111
79
77
74
76
71
69
Atomic Number
11
12
13
14
15
16
17
18
19
20
Atomic Radius
(picometers)
186
160
143
117
110
102
100
97
227
197
Ionization Energy for the First 20 Elements
Atomic Number
1
2
3
4
5
6
7
8
9
10
Ionization Energy
(kJ/mol)
1294
2336
511
886
787
1071
1380
1294
1656
2048
Atomic Number
11
12
13
14
15
16
17
18
19
20
Ionization Energy
(kJ/mol)
486
725
569
775
1046
985
1236
1496
408
581
Electronegativity Values for the First 20 Elements
Atomic Number
1
2
3
4
5
6
7
8
9
10
Electronegativity
2.1
No Value
1.0
1.5
2.0
2.5
3.0
3.5
4.0
No Value
Atomic Number
11
12
13
14
15
16
17
18
19
20
Electronegativity
0.9
1.2
1.5
1.8
2.1
2.5
3.0
No Value
0.8
1.0
Questions - Please answer with complete sentences.
Atomic Radius
1. What trends do you see in the data? (For example, what happens to the radius (size) of an
atom as you move across a Period (row) or down a row of the Periodic Table?
2. Explain the trends that you see based on your knowledge of atomic structure?
3. Check page 55-56 in your text book and look at the data that displays atomic radius and
ionic radius. What trends do we see in ionic radius? (For example compare cations with
anions and compare ions with smaller charges versus those with larger charges (for
example (Na+1 vs. Al+3)
Ionization Energy
1. What trends do you see in the data?
2. Explain the trends that you see based on your knowledge of atomic structure?
3. How are these trends different that those seen for Atomic Radius?
Electronegativity
4. What trends do you see in the data?
5. Explain the trends that you see based on your knowledge of atomic structure?
6. How are these trends different that those seen for Atomic Radius?
DUE: September 17, 2014
Marking Rubric
Communications
The graphs are correctly organized
 axes titles
 appropriate units chosen for number lines
 use of pencils, coloured pencils, ruler
 graph title
Data is accurately plotted
 data points are accurately positioned
 a trend line is added
 red lines are added to separate each period
Written answers are thorough, display clarity and use
scientific language
Inquiry
Trends are determined for each graph
 atomic radius
 ionization energy
 electronegativity
Each trend is explained based on knowledge of the
atomic structure of atoms
 atomic radius
 ionization energy
 electronegativity
The trends are compared accurately
R/I
1
level
2
3
4