In this lesson, students will watch a video and answer questions about how the molecular geometry and polarity of water give rise to many of its unusual physical properties, including its relatively high boiling point and its ability to dissolve some substances but not others.
Middle School, High School
This activity will help prepare your students to meet the performance expectations in the following standards:
- HS-PS1-3: Plan and conduct an investigation to gather evidence to compare the structure of substances at the bulk scale to infer the strength of electrical forces between particles.
- HS-PS2-6: Communicate scientific and technical information about why the molecular-level structure is important in the functioning of designed materials.
By the end of this lesson, students should be able to:
- Describe the bonding that takes place in water molecules and how it affects water’s structure.
- Explain how the bonding and shape of water molecules cause water’s high boiling point and relate to solubility of various substances in water.
This lesson supports students’ understanding of:
- Physical properties
- Covalent bonding
- Molecular geometry
- Intermolecular forces
Teacher Preparation: minimal
Lesson: 10 minutes
- The Chemistry of Water Video
- Student handout
- Computer and projector with sound and internet access
- No specific safety precautions need to be observed for this activity.
- The “The Chemistry of Water” video is part of the ACS video series Chemistry Basics.The entire series can be found here.
- The running time of this video is about two and a half minutes.It goes through information pretty quickly, so you may want to pause the video at certain points or play the video through twice.
- This video is intended for students to watch, and for teachers to integrate into their curriculum.
- The student questions/answers are presented in sequential order in the video.
- An answer key has also been provided for teacher reference.
For the Student
While watching the ACS Chemistry Basics video about the chemistry of water, answer the following questions:
- What kind of bonds are in water molecules?
- What shape does a water molecule have?
- Which atom in water is more electronegative, hydrogen or oxygen?
- Which element, hydrogen or oxygen, is the partially positive end of water molecules?
- What is the attraction between water molecules called?
- How do these attractions make water different from other similar compounds?
- What allows water to dissolve salt?
- What prevents water from mixing with oil?