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ACTIVITY in Introduction, Elements, Periodic Table, Identifying an Unknown. Last updated January 29, 2024.


In this activity, students use imaginary elements to create a periodic table based on patterns in the known properties of those elements. They then use these patterns to predict the properties of an unknown element.

Grade Level

High School

NGSS Alignment

This activity will help prepare your students to meet the performance expectations in the following standards:

  • HS-PS1-1: Use the periodic table as a model to predict the relative properties of elements based on the patterns of electrons in the outermost energy level of atoms.


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

  • Explain periodic trends.
  • Arrange elements appropriately based on their properties.
  • Apply periodic trends to unknown elements to predict their properties.

Chemistry Topics

This activity supports students’ understanding of:

  • Periodic table


Teacher Preparation: 5 minutes

Lesson: 20 minutes


For each group:

  • One set of element cards
  • One blank periodic table template


  • There are no special safety concerns for this activity.

Teacher Notes

For the Student



The periodic table is a special way of arranging elements based on predictable patterns in their properties and characteristics. In this activity, you will create a periodic table using imaginary elements. This periodic table should have appropriate trends across rows and groups of elements.


  1. On the next page, you will see a collection of elements along with their characteristics.
  2. Cut out each element card and arrange the elements in order based upon their characteristics, just like you would see on the periodic table. Use the attached periodic table template to organize the elements. (Note: Not all spaces on the template will be filled – there is a missing element!)
  3. After organizing your elements, use your periodic table to answer the analysis questions below.
  4. When you have finished, have your teacher check your work.

Analysis Questions

  1. Predict the state, color, and mass of the missing element. Explain your reasoning.
  2. Predict the mass of element Ia. Explain your reasoning.
  3. Predict the state, color, and mass of the element that will follow Az. Explain your reasoning.
  4. Bonus: Look at the element symbols used for these imaginary elements – do you notice something familiar about them? Explain the pattern and suggest a symbol (that does not match a real element symbol) for the missing element that fits this pattern.

Periodic Table Template