Water. It covers over 70% of the earth’s surface and even makes up about 60% of the human body. But did you know that water has some incredible properties that make it different from other liquids? This is due to water molecules’ unique molecular structure. If you are studying water in your classroom, here are a few fun water molecule activities to help your students “discover” some of water molecules’ weirder properties:
But first, here is a little background info on water molecules. We can think of water molecules as tetrahedral, meaning they behave like a 4-sided shape. Since two “sides” have slight positive charges and two sides have slight negative charges, the water molecules bond with one another. When bonded, the molecules arrange themselves into a hexagonal arrangement due to the angle between the sides of a tetrahedral form.
1. Build a water molecule activity
Build a model of a water molecule with a large marshmallow to represent an oxygen atom, small marshmallows to represent hydrogen atoms, and toothpicks to represent intramolecular bonds (bonds between hydrogen and oxygen within a molecule)
2. Molecular model of ice
After building a water molecule model (see above), continue on to build the hexagonal structure of ice! Add a second color of toothpick to represent intermolecular bonds (bonds between separate molecules) which cause ice to form. Try building a hexagonal ring from the molecules.
3. Volume change: ice vs water
Mark the level of water in a jar and then freeze it. Which takes up more room: liquid water or ice? Discuss how the unique hexagonal arrangement of molecules in ice keeps molecules farther apart than they are in liquid water. Relate this to density. You can also see that ice is less dense than water because ice floats in water.
4. Salt and water – melting point experiment
Experiment with salt’s effect on the melting point of ice. What impact might salt molecules have on the arrangement of water molecules within ice? Discuss why people may put salt on sidewalks and roads in the winter.
5. Consider my Science in the Snow Unit?
If you like these activity ideas, I think you’ll love my Science in the Snow Unit. It’s a complete set of interdisciplinary learning materials to help you teach a fantastic unit on the scientific study of snow and ice for your middle school or high school class. Students will learn about the molecular structure of ice, phase changes, snow water equivalent measurements, snow hydrology, weather stations, and more! Click the link below to learn more!
Bonus: Try this Free Saving Water Bingo Game!
Play this free Saving Water bingo game with your students. Click here to download and print it for free:
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