Summary

In this activity, students will use their knowledge of Periodic Trends to analyze and identify unknown elements and organize them correctly in the Periodic Table.

Grade Level

High school

Objectives

By the end of this activity, students should be able to

• Arrange known elements according to their properties on the Periodic Table.
• Identify unknown elements by reviewing their properties of atomic radius, malleability, ability to conduct, electronegativity, and ionization energy and using Periodic Trends to place them correctly in the Periodic Table.
  

Chemistry Topics

This activity supports students’ understanding of

• Periodic Table
• Periodic Trends
• Atomic Radius
• Electronegativity
• Ionization energy
• Physical Properties
  

Time

Teacher Preparation: 5 minutes
Lesson: 45 minutes

Materials (per group)

• Mendeleev Periodic Table Cards
• Scissors
  

Teacher Notes

• The Periodic Table Cards include all of the main block elements (groups 1, 2, 13-18) in the first five periods.  The cards include the following information:
  • Element name
  • Atomic radius
  • Malleability information
  • Conductivity information
  • Electronegativity
  • 1st Ionization energy
• You will find that 10 of the cards do not include the element name and they are shown as Unknown 1 – Unknown 10. Each student group should be given a set of cards and a pair of scissors. Give students the following instructions:

1. Cut out the element cards – there are 34 total cards that represent the main block elements (Groups 1, 2, 13-18) in the first five periods.
2. Arrange the cards that include the element’s name as they are arranged on the Periodic Table. There will be 10 blank spaces when they have completed this step. 
   
3. There is a simple Periodic Table included on the student activity sheet.  Do not let them access information from the Internet, textbook, or a more detailed Periodic Table.
4. They should then review the properties listed on the unknown cards and place the cards in the proper place using their knowledge of periodic trends and metallic properties.
5. When they have finished they should transfer their results to the activity sheet.
6. Groups should not communicate with each other.

• Note: The first three elements in group 13 and 16 do not follow the periodic trends for ionization energy moving across a row because of the way electrons are arranged in their orbitals. The cards for these six elements show the ionization energy as bold with an asterisk:  Ionization Energy = 578* kj/mol. If you do not address this anomaly in class, you may choose to remove groups 13 and 16 from this activity.
  
  
• Two sets of cards have been included with this activity.  One includes the 10 unknown elements. The other includes the names of all 34 elements and can be used as a template to customize this activity to fit the needs of your students.
  
  
• Optional: This activity can be used as a summative assessment.