Molecular Structure in Glacier Formation Mark as Favorite (0 Favorites)
ACTIVITY in Density, Physical Properties, Molecular Motion, Intermolecular Forces. Last updated March 31, 2025.
Summary
In this activity, students will model the compression of ice as a glacier forms. Students will make connections between density, distance between molecules, and the life of the glacier.
Grade Level
High School
NGSS Alignment
This activity will help prepare your students to meet the performance expectations in the following standards:
- Science and Engineering Practices:
- Developing and Using Models
Objectives
By the end of this activity, students should be able to:
- Model how glaciers become more compact over time, using water’s molecular structure.
- Correlate an increase or decrease in density to the change in a glacier over time.
Chemistry Topics
This activity supports students’ understanding of:
- Density
- States of Matter
- Molecular Structure
Time
Teacher Preparation: 20 minutes
Lesson: 30 minutes
Materials
- Magnetic Water Molecules Kit (one kit for every 2 students, if possible)
Safety
- None for this activity.
Teacher Notes
- This activity uses magnetic water molecule models to help students visualize the attractions between water molecules and the arrangement of water molecules in ice. Prior to completing this lesson, students should have been introduced to the properties of water – in particular, students should be able to identify that the partial positive charges on the hydrogens and partial negative charges on the oxygens result in strong attractions between molecules (hydrogen bonding), and that ice, water’s solid state, is less dense than the liquid state in contrast to most other substances in which the solid state is most dense.
- If properties of water have not been covered yet, students may not know that water molecules spread out when they freeze. This can be addressed to the whole class as a mini lesson if needed. The following resources are a good starting point if students need a refresher on the properties of water:
- Between steps 3 and 4, walk around and check in with each group of students about the structure of water when frozen.
- After Step 4, Pair and Share, consider asking a student to draw their drawing on the whiteboard or show it under a document camera for the class to see. Letting students check in with a classmate first helps them to feel more confident in sharing what they think.
- In Step 5, students need to be aware of the typical behavior of atoms/molecules in solids and liquids and how water molecules are atypical in that the solid state is less dense than the liquid state. (See the video and simulation above if students need to review this.) Make sure all students have the correct structure of frozen water molecules before they move on to step 6.
- The video “How do Glaciers Move?” does a great job summarizing some of the concepts involved in this activity. It may be help for you as the teacher to watch before the activity for more information or to show to students after they have completed the activity for a visual of glaciers. It could also help students understand the answer to the extension question
For the Student
Introduction
A glacier is a large build-up of crystalline ice, snow, rock, sediment, and often liquid water that forms on land and moves downhill due to its own weight and gravity. Glaciers typically form in areas with average temperatures close to water’s freezing point and lots of snowfall. Year-round snow coverage (more snow falls than melts) and frequent snowfall result in the presence of a large enough mass of snow that the weight of the top layers of snow is enough to compress lower layers of snow and begin the change from snow to glacier ice. Glacier ice is much more compact than snow, due to continual pressure from increasing snow mass over the years.
Source: USGS
Modeling Glacier Formation
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| Figure 1. Water molecules, bonds and attractions |
- Play a bit with the water molecules. Stick at least ten together. Draw a picture of the pattern they take in the space below. Use a dashed line to show an attraction and a shared border to represent a bond, as shown in Figure 1, for all your drawings in this activity.
- What do the magnets represent happening between the water molecules? Specify the atoms that line up when the magnets stick together.
- Make a prediction. When water is frozen, what will the molecules look like? Draw a sketch of the water molecules in the box below (Sketch A).
- Pair and Share. Show your drawing to a classmate sitting next to you. Do your drawings look the same? What different ideas did you have?
- Figure 2 shows how the particles in most substances behave in their solid, liquid, and gas states:
| Figure 2. States of Matter. Source: middleschoolchemistry.com |
- How does the structure of water molecules when frozen compare to other solids?
- Place a handful of water molecules in your hand and clasp your hands around them tightly. What do the water molecules do? Draw a sketch of the water molecules in the box below (Sketch B).
- Compare the density of the frozen water between sketch A and sketch B. Which is denser? Explain.
- Compare the density of the frozen water between sketch A and sketch B. Which is denser? Explain.
- Which sketch is more likely to represent the type of ice deep in a glacier – sketch A or sketch B? Explain your answer.
- If you were given two chunks of ice of the same size, one from near the surface of a glacier one from deep within the glacier, which would have a greater mass? Which would have a greater density?
- In the case of glaciers, what type of force causes water molecules to become more compacted?
- Extension: Make a prediction. How can a glacier “flow” down a hill when it is solid with little to no air trapped between molecules? Explain your answer using molecular structure.