Name:
Periodic Trends Lab
Introduction
In 1869, aware of the need to organize elements in a meaningful way, Dmitri Mendeleev
developed a classification scheme based upon increasing atomic mass. Elements that
demonstrated similar patterns of chemical behavior were placed into eight groups. Members of
these groups were displayed in vertical columns of his periodic table. Even though his chart was
incomplete, Mendeleev was able to predict the properties of elements yet to be discovered. Over
the next two years, Mendeleev published modified versions of his original periodic table.
Today’s periodic table accommodates at least 50 additional elements. Although the
scheme is based upon increasing atomic number, the arrangement of elements within the chart is
similar in organization to the table published by Mendeleev in 1871. Trends in the chemical and
physical properties of the elements may be seen as a periodic function of electron configuration.
In this exercise, you will examine several properties of elements and observe how these
properties may be interpreted with respect to periodic law. Your knowledge of the modern
periodic table and facts about the elements will then allow you to construct the periodic table
published by Mendeleev in 1871.
Procedure
Using Table S of the Reference Tables, obtain The following data for elements #1-36: Atomic
Radius, Ionization Energy, and Electronegativity. Use the data table on the following page to
organize your data.
Plot the following graphs.
a. Atomic Number on x axis vs. Atomic Radius on y axis
b. Atomic Number on x axis vs. Ionization Energy on y axis
c. Atomic Number on x axis vs. Electronegativity on y axis
On each graph, indicate by using colors or different symbols the members of Group 1, Group 2,
and Group 18.
Analysis
Look at your graph of Atomic Number vs. Atomic Radius.
1. As the atomic number increases from left to right across the period, the atomic radius ______________
2. As the atomic number increases from top to bottom in a group, the atomic radius _________________
Look at your graph of Atomic Number vs. Ionization Energy.
1. As the atomic number increases from left to right across the period, the ionization energy ___________
2. As the atomic number increases from top to bottom in a group, the ionization energy ______________
Look at your graph of Atomic Number vs. Electronegativity.
1. As the atomic number increases from left to right across the period, the electronegativity ___________
2. As the atomic number increases from top to bottom in a group, the electronegativity _______________
Questions
1. What factor may account for the observed trend in atomic radii as one proceeds across a
period?
______________________________________________________________________
2. What factor may account for the observed trend in atomic radii as one proceeds down a
group?
________________________________________________________________________
3. Explain the reason for the trend in ionization energy across a period.
________________________________________________________________________
________________________________________________________________________
4. Explain the reason for the trend in ionization energy down a group.
________________________________________________________________________
________________________________________________________________________
5. Explain the reason for the trend in electronegativity across a period.
________________________________________________________________________
________________________________________________________________________
6. Explain the reason for the trend in electronegativity down a group.
________________________________________________________________________
________________________________________________________________________
7. Which group appears to have members of the largest atomic radii? __________________
8. Which group appears to have members of has the smallest atomic radii? _____________
Data
Atomic
Number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
Atomic Radius
Ionization
Energy
Electronegativity