This lesson introduces students to the periodicity of elements. It serves as the engagement aspect of the learning cycle. First, students use teacher-prepared index cards of the first 20 elements, arrange them by atomic mass, and "create" patterns within the 20. In order to test their "created" patterns, they compare them with the periodic table as organized by scientists. To achieve this, they color-code their periodic table, following teacher instructions, and visualize the trends. Each student then works with a partner and shares the patterns they observed. This activity gives students a framework for exactly that of which our world and humans bodies are "made".
Physical Science: An element is composed of a single type of atom. When elements are listed in order according to the number of protons (called the atomic number), repeating patterns of physical and chemical properties identify families of elements with similar properties. This "Periodic Table" is a consequence of the repeating pattern of outermost electrons and their permitted energies.
Prior to this unit, students will need a general understanding of atomic structure.
a. Time frame: Two class periods (Approx. 90 minutes)
b. Materials: Set of index cards, student copies of Periodic Tables, colored pencils, markers or crayons, resources demonstrating trends of the periodic table. (A chemistry textbook or http://pearl1.lanl.gov/periodic)
c. Resources: Chemistry Text Books or the following www sites:
http://pearl1.lanl.gov/periodic (general introduction to and trends of the periodic table)
http://www.modlife.com/MLG/body.html (human body chemistry)
-Student engagement activity: Distribute sets of index cards to each pair of students. For schools using ChemCom, page 59 of the teacher's edition provides a copymaster for these cards. Otherwise, a series of cards listing atomic mass and some other common physical/chemical properties of each element should be prepared for each pair or group of students. For a sample card, select the link for group trends card. Have students follow the directions in the student activity (see student web page).
-Teacher-led Discussion: Have student share their grouping ideas from the card activity. Then indicate to them that they will compare their patterns with patterns used all of the time by scientists. Distribute student copies of the Periodic Table. Introduce the periodic table as representing all known material that makes up our planet.
-Individual Student Activity: Provide each student with a generated list of Periodic Table families to be identified and color coded (ie. alkali metals, alkali earth metals,boron family, carbon family, nitrogen family,oxygen family, halogens, noble gases, transition elements,lanthanides, actinides, metals, nonmetals, mettaloids,solids, liquids, gases). Instruct students to use the identified resources in "c" above to color code their periodic table.
-Partner Sharing: After giving students time to complete this task, have them work with one other student (the same student with whom they worked on the "card" activity) to compare and contrast trends. Instruct them to be ready to share their understandings with the whole group.
-Whole class discussion: Use teacher-guided questioning to facilitate a class discussion of trends. In this discussion, include specific examples of elements and their impact on the human body (see resource in "c" above), in order to allow students to make connections among the human body, health and the periodic table. Instruct students to keep their coded periodic tables throughout the semester.
-Connecting activity: The following class period should begin with teacher feedback based on the assessment exit cards. Any student misconceptions should be addressed. Students who have completed the enrichment homework activity (see enrichment below) can share those results at this time.
8. Assessment (lesson specific):
a. Students peer-check their patterned cards and each other's color-coded periodic tables.
b. Teachers use an "exit card" to determine levels of understanding from each individual student. This "exit card" could have five to 10 questions related to specific trends found on the periodic table or a general writing prompt ("The trends of the periodic table are...) which students will answer. Use this information to determine students' misconceptions and level of conceptual understanding. It need not be graded as "right" or "wrong", but should be used to determine how well the previous activity helped students learn.
World Wide Web resources on the Periodic Table are readily accessible to all students with computer based classrooms.