Snow Cool!

Winter is just around the corner, and what’s better than learning about the chemistry behind snowflakes? You’ve probably heard of Snowflake Bentley, and how he photographed different snowflake shapes. We are photographing snowflakes, but there’s more to a snowflake than just the outside. So let’s go outside, into the world of the widely sung about white wonderland!

Snowflakes are a form of water ice. They form in clouds, which are made up of water vapor. At  32° F (0° C) or colder, water turns to ice. Temperature can influence snowflakes, as well as currents, humidity, and dirt and dust particles. The dirt makes the snowflake heavier, which can make it easier to melt.

I found some great information on one website about what snowflake shapes are created when:

  • 32-25° F – Thin hexagonal plates (high clouds)
  • 25-21° F – Needles (middle height clouds)
  • 21-14° F – Hollow columns
  • 14-10° F – Sector plates (hexagons with indentations)
  • 10-3° F – Dendrites (lacy hexagonal shapes) (low clouds)

Colder temperatures produce snowflakes with sharper tips on the sides of the crystals and may lead to branching of the snowflake arms (dendrites). Snowflakes that grow under warmer conditions grow more slowly, resulting in smoother, less intricate shapes. However, not all snowflakes are symmetrical, as many conditions can effect the balance and appearance of a snowflake. Some can be, of course, as its shape represents the order of the water molecules within the snowflake. Based off one site, “Water molecules in the solid state, such as in ice and snow, form weak bonds (called hydrogen bonds) with one another. These ordered arrangements result in the symmetrical, hexagonal shape of the snowflake. During crystallization, the water molecules align themselves to maximize attractive forces and minimize repulsive forces. Consequently, water molecules arrange themselves in predetermined spaces and in a specific arrangement. Water molecules simply arrange themselves to fit the spaces and maintain symmetry.” Basically, hydrogen bonds are formed from water molecules, which are aligned in a symmetrical way. During crystallization, water molecules move into certain spaces to fit.

In chemistry class, we recently discussed quantum numbers. The idea of the fourth quantum number, the spin quantum number, talks about the direction of the electrons within an atom on a given energy level. This means that while the energy levels, the axis, and the orbitals can be the same, the spin will change. This is one of the reasons why no two snowflakes are the same, among other factors like the number of water molecules and the isotope abundance of hydrogen and oxygen. As we cannot individually look at every single snowflake in the world (that would be awesome), there have most likely been identical, or very near to it, snowflakes. However, in your lifetime, you will most likely never see two identical snowflakes. Sorry!

Snow is white, right? Well… Long story short. Our eyes are playing tricks on us, so we see white light being reflected off the snowflake’s many surfaces. Based off one source, ” Even though the light source might not be truly ‘white’ light (e.g., sunlight, fluorescent, and incandescent all have a particular color), the human brain compensates for a light source.” That also explains why polar bears’ fur appears white.

I have always loved snow, from building snowmen to jumping and playing in giant piles of snow. My sister and I would keep the snow as neat as possible, stepping in each other footprints. I remembered learning about Snowflake Bentley in class, and, now that I am older, I might as well learn the chemistry behind snow. It has been really interesting to learn about the different shapes, because I never thought about why snowflakes are always portrayed in only one way. That’s why we would make the paper snowflakes, where you cut out holes using scissors. To make the craft, follow instructions below!

Craft:

Materials:

  • copy paper or thicker type of paper if you want.
  • scissors, preferably sharp (safety scissors for younger children are fine, too! 🙂 )
  • glitter and glue (optional)
  • string or tape (optional)
  • nearby garbage to place scraps in

Procedure:

  1. Fold the paper into a square, triangle, or any other shape, so long as it folds evenly. (I personally suggest a triangle shape) It should easily fold 3-4 times.
  2. Carefully cut out holes, triangles, squares, diamonds, etc. out of the paper. You can cut along the edge or in the middle. Get creative!
  3. Unfold it! Voila! You have made your very own snowflake! Feel free to edit as you like.
  4. For extra pizzazz: put some glue on one side of the snowflake and carefully put glitter on it. You may want to put a paper plate or paper towel underneath to catch excess glitter. Lay it out to dry.
  5. You can tape or hang your masterpiece using string or tape. Enjoy!

Link:

http://chemistry.about.com/od/moleculescompounds/a/snowflake.htm

So ta ta for now and I hope to see your chemical reaction soon!

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