Summary

In this activity, students will view an animation that explores how different chemical bonds form. Examples of ionic, covalent, and polar covalent bonds are animated, and then students are given a sample of compounds to predict the bonding types.

Grade Level

Middle School, 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.
• HS-PS1-2: Construct and revise an explanation for the outcome of a simple chemical reaction based on the outermost electron states of atoms, trends in the periodic table, and knowledge of the patterns of chemical properties.
• Scientific and Engineering Practices:
  • Developing and Using Models

Objectives

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

• Identify substances as having ionic, covalent, or polar covalent bonds.

Chemistry Topics

This activity supports students’ understanding of:

• Ionic and covalent bonding
• Lewis structures

Time

Teacher Preparation: minimal
Lesson: 10-30 minutes

Materials

• Computer and projector with internet access
• https://teachchemistry.org/classroom-resources/bonding-animation
• Student handout

Safety

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

Teacher Notes

• All of the animations that make up the AACT Animation collection are designed for teachers to incorporate into their classroom lessons. Intentionally, these animations do not have any spoken explanations so that a teacher can speak while the animation is playing and stop the animation as needed to instruct.
• If you assign this to students outside of class time, you can create a Student Pass that will allow students to view the animation (or any other video or ChemMatters article on the AACT website).
• We suggest that a teacher pause this animation at several points or watch it more than once to give students the opportunity to make notes, ask questions, and test their understanding of the concepts presented. The animation is a little over 1 minute long and moves quickly, so students will likely require pausing or multiple viewings to successfully complete the student activity sheet if you choose to use it.
• This animation can be used as a brief introduction to bonding, but if you use the student activity sheet it might be helpful for students to have already had some instruction on bonding. In any case, prior to using this animation students should be able to identify metals and nonmetals and understand what valence electrons are. They should have a periodic table available.
• If students are not already familiar with the octet rule (and the duet rule for hydrogen) and Lewis structures, this animation could be used to introduce these topics.
• Students will probably recognize that metal/nonmetal pairings of elements form ionic bonds, but they may have a harder time differentiating between covalent and polar covalent bonds since both involve nonmetals. Even if you have not discussed electronegativity yet, the polar covalent bond examples provided in this animation (H₂O and NH₃) show the asymmetry required for a molecule to be polar, and the covalent bond examples (CCl₄ and Cl₂) are both symmetrical. You can discuss that in the polar molecules, the electrons are unevenly distributed, in part because of the asymmetry of the molecule (in addition to electronegativity differences).
• This animation does not spell out the difference between polar bonds and polar molecules. Depending on the level of your students, you may want to address the fact that a molecule can have polar covalent bonds but still be a nonpolar molecule if the bond dipoles are symmetrical in all planes and therefore cancel one another out. This LibreText page compares CO₂ and H₂O and might help students visualize the difference between polar bonds and polar molecules.
• The first extension question provides an opportunity to discuss the differences in the ways ionic compounds and molecular compounds are structured. Ionic compounds have lattice structures comprised of repeating patterns of alternating cations and ions held together by the strong electrostatic attraction between them. Molecular compounds are composed of individual molecules that contain nonpolar or polar covalent bonds, and these molecules interact with each other (through various types of intermolecular forces) less strongly than ions do. This could lead to a discussion on how the structure of a compound can affect its properties – for example, ionic compounds are held together very tightly by the electrostatic attractions between ions and as a result have much higher melting and boiling points than most molecular compounds.
  • The Intermolecular Forces simulation is a popular AACT resource that describes the relative strengths of intermolecular forces in molecular compounds and how these forces affect physical properties, such as boiling point and vapor pressure.
• If your students are already familiar with Lewis structures, you could broaden the second extension question to include drawing Lewis structures for the example compounds they list.
• Related classroom resources from the AACT Library that may be used to further teach this topic:
  • Simulation: Ionic & Covalent Bonding
  • Unit Plan: Chemical Bonding Unit Plan
  • Lab: Lego Modeling of Compounds
  • Activity: James Bonded
  • Activity: Formula Card Game