Summary

In this activity, students will receive a deck of cards with images of aliens with various physical features that they have to organize into groups and periods following patterns in those features. Two cards are removed from each deck, and after students organize the cards, they can predict (draw) the missing aliens. They then watch a short video about Mendeleev to help them relate their process for organizing their alien cards to how Mendeleev organized the elements of the periodic table and predicted where undiscovered elements would fit.

Grade Level

High School

NGSS Alignment

The teaching resources used in this unit plan 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.
• Scientific and Engineering Practices:
  • Analyzing and Interpreting Data
    

Objectives

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

• Understand how the periodic table is organized by organizing drawings of aliens.

Chemistry Topics

This activity supports students’ understanding of:

• Periodic table
• Trends of the periodic table

Time

Teacher Preparation: 10 minutes
Lesson: 30-40 minutes

Materials

• A stack of alien cards for each group (see PowerPoint to create class sets—slides 2-3 or 7-8)
• Student handout
• Computer, internet, and projector with sound, for watching video (or assign for homework)

Safety

• No safety precautions need to be noted for this activity.

Teacher Notes

• This activity is a fun way to introduce students to the concept of periodic trends. Students will receive a set of cards with drawings of aliens with a couple of the cards removed. The aliens have different physical characteristics (number of fingers, body shape, number/shape of hairs, etc.) and students are tasked with finding the patterns in these characteristics and organizing the alien cards based on those patterns. They will then predict where the missing cards would fit and what they would look like. Students should work together in small groups of 2-4.
  • For increased difficulty, remove more cards from the deck.
• Mendeleev used a similar process of sorting elements by their physical and chemical properties to predict the yet undiscovered elements on the periodic table by using the properties of the elements around it. To help students make the connection between their aliens and real elements, consider following this activity with Mendeleev’s Periodic Table, which has students complete a similar task of identifying and placing missing elements based on their properties, or a similar resource using fictional elements, Make a Periodic Table.
• To help students keep track of their cards and improve the longevity of the cards, you could print them on colored card stock and laminate them.
• Remove two cards from each deck and make sure cards are shuffled before distributing decks to students. Have them group the cards, look for patterns, and draw the missing aliens. You could just have students identify the missing aliens and discuss their process, or you could also have them complete the student handout that has them think about their process in a more structured way and make connections to how a similar process could be used for organizing elements, like Mendeleev did.
• The final table has 5 periods and 8 groups (families). You may wish to tell students that their final arrangement should be wider than it is tall, so that when they refer to “columns” and “rows,” everyone is oriented the same way. (They could end up with a correct pattern if they organize the cards into 8 periods and 5 groups, but this would not line up with the real periodic table and the parallels to the real periodic table described below would not work as well.)
• Some of the alien features have parallels to properties of elements in the periodic table, which you may want to share with your students, or you could revisit this activity after students have learned more about the organization of the periodic table:
  • The number of fingers increases as you move from left to right (this represents number of valence electrons)
  • The hair or number of legs or foot length increases as you move from top to bottom (this represents energy level of atoms)
  • Note that some of the aliens in columns 6, 7, and 8 of the cards only have one eye. This is intended to represent a division between metals (two eyes) and non-metals (one eye) but may be confusing for students. If you do not want to address this parallel to the real periodic table with your class, you may wish to edit the alien sketches in the PowerPoint file before printing so that all of the aliens have two eyes.
• An example of an incorrect alien table is included in the PowerPoint (slide 5).
• The conclusion has students watch a short video and reflect on the similarities in their process with the alien cards to what Mendeleev did when trying to organize the elements. This can be completed as a whole class watching the video together in class, or it can be assigned for homework.
• The AACT website includes many more resources for teaching periodic trends and the periodic table – see the Periodic Table Unit Plan for some of the most popular ones.