The Periodic Table as a Tool for Teaching Scientific Literacy

According to the National Science Education Standards (1996), students in grades 5 to 8 are expected to use the properties of matter to distinguish and separate one substance from another. Showing students the underlying features of the organization of the Periodic Table of the Elements helps to accomplish this goal, but it is a daunting task and often not very meaningful to students. From a student perspective, understanding the multiple relationships shown in the periodic table can be overwhelming and abstract. Teachers can help students understand the patterns in the Periodic Table of the Elements using two strategies detailed in the following activity: connecting familiar ways of organizing to scientific organizing and demonstrating the way the periodic table is organized.

Object Organization Activity

Students often enter the science classroom thinking that they do not understand science, but people naturally seek out patterns and explanations, which is a central function of science. This activity begins by asking students to use their prior knowledge to classify simple objects. The objects are paper cut-outs with five different attributes – shape, color, borders, size, and labels (see Figure 1). Working in groups of three or four, students are given a sample graphic organizer that includes an example using color as an organizing system (see Figure 2). The students are then asked to be creative and find four other ways to categorize the same objects and to write their information on a graphic organizer.

The groups take turns reporting out on a unique classification system of their everyday objects to the rest of the class. Some of the organization systems given by students will sort the objects into several equally distributed groups and some organization systems will arrange the objects into one group that includes most of the objects and another group that includes the remaining few objects. At this point, the teacher asks the students “Which organization system is more useful?” The pursuant discussion can be helpful in showing students why a scientist might want to organize the objects into more equally distributed groups and conversely, why a scientist might want to isolate a member from a group.

Connections to the Nature of Science

Teaching factual science knowledge without teaching how the knowledge can be acquired rarely allows students to think above the recall level. When students are required to memorize facts of the Periodic Table they are not given the opportunity to learn how to learn. A more meaningful method of teaching the properties of matter is to have students understand why the Periodic Table is organized the way it is and to be able to use it as a tool to look up information about the elements. When students understand the principles under which scientists construct knowledge, they have the power to construct their own knowledge (Brooks & Brooks, 1999).

After the object organization activity, students have a basis for understanding why organization is useful and how something can be organized in multiple ways using different attributes. Students will learn about an important organizational tool used in science, the Periodic Table. As called for in the Benchmarks for Scientific Literacy (1993), students in this activity are guided from the concrete activity of organizing objects to a more abstract one, categorizing elements on cards into different systems.

Element Organization Activity

Groups of four students are given the same set of cards that have information about chemical elements such as symbol, name, atomic number, number of valence electrons, atomic radius, and general physical properties for each element from atomic number 3 to atomic number 20 (see Figure 3). Students are asked to decide on one organization system for their deck of cards and justify why they chose their categories. When all groups have reported out their choice for organization of the cards to the entire class (see Figure 4 for examples), the teacher asks students which types of organization are based in nature (scientific) and which systems are based on human constructs such as alphabetical order. Some questions that can get student discussions initiated are:

1. What might be some criteria that would make one grouping system more useful than another?

2. Are some grouping systems that you named more useful than others?

3. If the grouping systems are equally valued for their usefulness, how would a scientist choose which system to follow?

4. How might scientists agree on which system to follow?

This discussion allows students to think about the decisions that scientists must make in constructing a common organization system for use understanding science.

Seeking patterns

After the student discussions, the teacher tells the class that there is one known organization system for chemical elements that allows for many different properties to be grouped together and that the following part of the activity will help them discover that system. The teacher asks the students to line ups the cards in order of atomic number. When students have the cards lined up, they look for other patterns that occur due to arrangement of the elements by atomic number. Students recognize several patterns: valence number is increasing by one until it gets to eight, then begins again, atomic radius decreases, then increases and begins to decrease again, or properties of the elements also form a repeating pattern.

Students begin to realize that by ordering the elements by atomic number, that other types of organization systems develop naturally, reinforcing the idea that patterns occur in nature and it is the role of scientists to find and describe these patterns. At this point in the lesson, it is important that the teacher connects the idea of repeating patterns to the vocabulary “periodic”.

Periodicity is then extended to everyday life by prompting students to give examples of things in their lives that form repeating patterns. They often respond with examples such as meal times, the days of the week, or the months of the year. If it isn’t brought up by a student, the teacher can ask for an alternate name for “classes”, which is “periods”. Students attend first period, then second period, then third period, and so on. Each day the pattern repeats again, just as it does in the periodic table of the elements. Because information from students’ everyday lives is connected to abstract scientific information, the name “Periodic Table of the Elements” has much more meaning.

Students compare their card organization with the structure of the periodic table and observe that the periodic table is organized in the same way. The Periodic Table of the Elements is structured to give a great deal of information if the observer understands what to look for. Since students construct knowledge about the underlying patterns that are formed when the elements are put into order by increasing atomic number, they have access to the Periodic Table of the Elements as a tool to look up information about elemental features.

Mendeleev’s Process

This activity can also be extended to teach students about the history of science. Teachers can discuss Mendeleev’s Process with students after the activity or assign a small research paper for students to discover Mendeleev’s process. When students know more about the process of card sorting that Mendeleev used in developing his system for the periodic table, they can have a deeper understanding about the nature of science (Duschl, 1990). See Figure 5 for more extensions of this activity.

There were several versions of the table of the elements before Dmitri Mendeleev proposed his adaptation (Sterling, 1996). Being an enthusiastic card player, Mendeleev wrote the 63 known elements in his time on separate cards and repeatedly laid them out to discover patterns. He realized that when he ordered the cards by atomic mass, as atomic number was not known in 1869, that chemical and physical properties of the elements formed a repeating pattern. From his version of the Periodic Table, Mendeleev predicted the existence of several undiscovered elements, which were found later during his lifetime. The scientific community continues to use Mendeleev’s basic idea for the periodic table of the elements with the exception of ordering the elements by atomic number rather than atomic mass, because it has been the most useful organization system to date.

Connections to National Standards

The activity described in this article addresses both teaching standards and content standards from the National Science Education Standards (1996) and from The Benchmarks for Science Literacy (see Figure 6). It is an inquiry-based activity that utilizes student logical construction of knowledge to find and use patterns that follow scientific principles. The progression of ideas involved in these activities help to bring together ideas of science content and scientific processes in developing knowledge while transitioning from concrete to abstract knowledge.

Process and Content Connected

When students are given only factual knowledge, two major conflicts occur. The first is that students do not feel responsible for constructing knowledge because they are being fed facts by the teacher. Students feel that the information that constitutes knowledge is fixed and only available to authorities such as teachers, so they passively wait for their education. Another conflict occurs when students are given scientific facts as if they were in the final form, and then told that ideas in science change over time. When students are given the opportunity to find out how scientific knowledge is gained as well and the knowledge itself, then students are empowered to construct knowledge actively. As a result of participating in this series of activities, students are exposed to both the factual knowledge that is provided by the Periodic Table of the Elements and to the scientific processes and habits of mind that are required to produce scientific knowledge.

References

American Association for the Advancement of Science. (1993). Benchmarks for science literacy. New York, NY: Oxford University Press.

Brooks, J. G. & Brooks, M. G. (1999). The case for constructivist classrooms. Alexandria, VA: Association for Supervision and Curriculum Development.

Duschl, R. A. (1990). Restructuring science education: The importance of theories and their development. New York, NY: Teachers College Press.

National Science Foundation. (1996). National science education standards. Washington, DC: National Academy Press.

Sterling, D. R. (1996, October). Discovering Mendeleev’s model. Science Scope. 26-30.

Figure 1

Object organization activity attributes

Shape	Color	Border/No Border	Size	Labels
Rectangle	Blue	No border	Small	None
Rectangle	Red	Border	Large	X1
Rectangle	Yellow	Border	Large	Y1
Circle	Blue	No border	Small	Z1
Circle	Yellow	Border	Large	None
Circle	Red	Border	Large	X2
Square	Blue	Border	Small	Y2
Square	Yellow	Border	Small	Z2

Figure 2

Sample graphic organizer for categorizing objects by color

System: Color

Categories	Members
Red
Blue
Yellow	Z2 Y1

Note to the Editor: For greatest clarity Figure 3 needs to be reproduced with the object in color – red, blue, and yellow.
Figure 3

Example of Element Cards

Figure 4

Possible Element Card Arrangements

Category	Systems	Type of categorization
Alphabetical by Name	A-Z by name of element	Non-scientific
Alphabetical by Symbol	A-Z by first letter of symbol	Non-scientific
Number of letters in symbol	One letter or two letters	Non-scientific
Atomic number	2-20	Scientific
Valence number	Group with 1 valence electron, group with 2 valence electrons, group with 3 valence electrons, and so on	Scientific
Atomic radius	Ascending or descending atomic radius	Scientific
Properties	Groups with similar properties	Scientific

Figure 5

Possible Extensions of Activity

Write a summary paragraph

Reflecting on the information you learned today, write a paragraph using the following words to explain how the Periodic Table of the Elements is organized.

· Organization

· Scientific

· Elements

· Periodic

· Valence electrons

· Atomic number

· Properties

· Atomic Radius

Write an editorial supporting Mendeleev’s prediction of missing elements

Before the predicted elements were found, Mendeleev’s hypothesis that elements needed to follow a pattern was controversial. Many scientists did not think that organizing elements by property was enough evidence to predict unknown elements. Suppose you lived during that time period, write an editorial article to the local newspaper supporting Mendeleev’s predictions.

Make a periodic table of food

Given 12 different dried foods such as beans, rice and pasta, create a periodic table of food. Be sure to organize your food groups in as many ways as possible. You can even find the “atomic mass” of each food by using a balance to measure the average mass of one “atom” of each type of food.

Investigate the properties that are common to each group of elements

The Periodic Table of the Elements organizes elements in a column called “groups” or “families”. Use library materials to research the common features of each group on the periodic table. How could you include this information in today’s activity?

Figure 6

National Science Education Standards

Standard	Description of Activity
Teaching Standard A: Inquiry-based program	Organizing everyday objects helps to connect scientific organization to student prior knowledge
Teaching Standard B: Teacher facilitated science activity	Students create simplistic systems of organization and through activities begin to see the sophistication of the organization system of the Periodic Table of the Elements
Content Standard K-12: Unifying Concepts and Processes	Understanding of the criteria for using scientific principles for organizing the Periodic Table of the Elements
Content Standard A: Science as Inquiry	Using logic without having to follow a step-by-step method
Content Standard B: Physical Science	Properties of Matter

Benchmarks for Science Literacy

Benchmark	Description of Activity
1A: The Scientific World	Student evaluation of scientific merit of organization systems
1B: Scientific Inquiry	Imagination plays a part in making sense of collected evidence
4D: The Structure of Matter	Finding patterns in the properties of matter