Chemistry Now, the chemistry of crystals: ice, salt

Snow flake against black background.The way a crow
Shook down on me
The dust of snow
From a hemlock tree

Has given my heart
A change of mood
And saved some part
Of a day I had rued.

Like Robert Frost in Dust of Snow, seeing the individual crystalline shape of a tiny snowflake always brings a smile to my eyes. Yes, no two are alike, so that’s a LOT of smiles! The National Oceanic and Atmospheric Administration (NOAA) explains that each crystal (initially formed around a particle of dust or a pollen grain) falls through a slightly different path of atmospheric conditions, so the resulting patterns are slightly different.

But snowflakes are always six-sided. Why? Visualize this for students using the Chemistry of Ice video, part of The Chemistry of Crystals learning package from NBC Learn and its partners NSF and NSTA. This learning package explores the molecular nature of crystals through ones students use every day—ice and salt. Look through the various assets in this learning package. You’ll find plenty of places to insert them into your instruction. Then, leave comments to let us know how they worked for you.

–Judy Elgin Jensen

Photo of snowflakes by Andrew Magill.

Video: Chemistry of Ice”  explains how the molecular structure of H2O changes as it reaches its freezing point, and turns from a liquid to a less dense solid crystal lattice.

Video: Chemistry of Salt (NaCl)” explains and illustrates the molecular structure of sodium chloride (NaCl) crystals; the structure and symmetry of crystal lattices; and why one crystalline solid, salt, melts another, ice.

Video: Think of “Molecule Profile: H20—Water” as a “highlight reel” of animations and facts about water.

Video: An NBC Weather News report, “Record Breaking Storm Slams Mideast to Northwest” tracks dangerous winter conditions from February 2011 across nine states.

Video: The NBC News report, “How Snowflakes Form” highlights 1986 research at the Schlumberger-Doll Research Lab that visualizes the NOAA description.

Video: The NBC News report, “Alternatives to Road Salt: Liquid Made from Beets” describes an environmentally friendly way to extend salt reserves in winter weather.

Video: The NBC News report “Crystals, Bouncing X-Rays and Atoms: An American Chemist and the Nobel Prize,” profiles Herbert Hauptman and his work on developing direct methods for the determination of crystal structures, which led to the 1985 Nobel Prize in Chemistry that he shared with Jerome Karle.

Middle school lesson: In this lesson, students explore mixtures and solutions and determine how to separate the components of salt water.

High school lesson: In this lesson, students will design an experiment to quantify effectiveness of different salts in melting ice at different temperatures.

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