There are residual forces between molecules ("Skeletal chemistry" 5 of 9)
"Such interactions result in the formation of condensed matter. And thus we have taken the leap from molecules to bulk matter. This step is a crucial part of our understanding of matter because, from the reverse point of view, it means that we can understand the properties of macroscopic samples in terms of their microscopic components."
Crystal Creations: Grow Spikes of Crystals in the Sun
Dissolving Epsom salt in water and leaving it out in the sun causes needle-shaped crystals to form as the water evaporates.
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Comparing Crystals
The crystals of table salt, Epsom salt, and sugar form different types of crystals, since each one forms a different structure.
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Fold a Crystal
To get at the variations in crystal shape, here are some common crystal structures to print out and fold up.
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What's So Special about Water: Surface Tension
Water molecules are attracted to the parts of the sugar and salt crystals, which is why they dissolve. But the water molecules are also attracted to each other. Here are three short activities demonstrating how water molecules "stick together."
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Meltdown
Liquid water can turn into water vapor through boiling or evaporation. It can also turn into ice through freezing. This video makes nice use of molecular models to address the ice/water relationship.
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Hexagon Hunt
This activity includes a suggestion for looking at snowflakes to see their hexagonal crystal structure. This might only work well for people in climates where it snows, but it does show how a basic crystal structure (hexagonal) allows for tremendous variation in appearance.
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"Skeletal chemistry" article
This is one of the nine central ideas that Peter Atkins lays out in his 2005 article, "Skeletal chemistry." Each of the other ideas has its own list in SMILE.