Summary

In this activity, students will find the electronegativity values of a variety of elements, draw the Lewis structures of select molecules that are made with those elements, and identify the molecular shape of each molecule. Students will then be asked to determine if the molecules are polar or nonpolar based on the electronegativity values of the atoms and the molecular shape. Students will use Ptable.com to find information about atoms and molecules and connect what they find to observable properties.

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.
• Scientific and Engineering Practices:
  • Developing and Using Models
  • Analyzing and Interpreting Data

Objectives

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

• Relate the shape of a molecule and the relative electronegativity values of its constituent atoms to the polarity of the molecule.
• Describe the properties and functions of common molecules.
• Draw Lewis structures of a molecule based on the molecular formula.
• Identify the shape of a molecule based on the Lewis structure.

Chemistry Topics

This activity supports students’ understanding of

• Periodic trends
• Electronegativity
• Molecular shape
• Polarity

Time

Teacher Preparation: 10 minutes

Lesson: 60 minutes

Materials

• Computer for each student or pair of students
• Access to the internet
• Handout for each student (either electronic or paper)

Safety

• No specific safety precautions need to be observed for this activity.

Teacher Notes

• This activity is designed so that students will make connections between the concepts of electronegativity, molecular shape and polarity. Students should have been introduced to these concepts before this activity.
• Students also need to be familiar with the Ptable.com web interface. If they have never used it before a brief overview of where to find the different tabs, how to scroll over elements to get more information, and where to find specific information would be helpful at the beginning of the activity.
• Depending on the students’ familiarity and comfort level with Lewis structures, more complicated molecules may be substituted for those suggested here.
• At the end of the activity, the teacher can wrap up by having students review the Lewis structures, molecular shapes, polarities, and interesting facts with the class. During this discussion, the teacher can point out any connections between the molecular properties and the interesting facts the students share.
• An answer key document is provided and available for download for teacher reference