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Beautiful Chemistry: Molecular Structures
These models show the structures of some basic molecules such as water and carbon dioxide, then move on to show more complex molecular strautures.
American Chemical Society
Middle School Chemistry: Lesson Plans: Why Does Water Dissolve Salt?
Students use their own model of a salt crystal and water molecule to show how water dissolves salt. Then, they relate their observations to the structure of salt, water, and alcohol on the molecular level.