Seperating Molecules

Today my Physical Science students and I were discussing atoms and molecules.  The point of the lessons was not simply that a molecule is a combination of different atoms, but really understanding that these combinations then make up unique substances with characteristics of their own.  We started with water, a great starting point because kids are familiar with it, and are most often familiar with the chemical equation for water..H2O. They can observe that water is different than oxygen or hydrogen and has it’s own unique characteristics.

We explored these concepts with a simple experiment.  (This experiment does use electricity, so use commonsense safety precautions.) We took two copper wires with their ends exposed and attached one end of each wire to the top of a 9 Volt battery, using electrical tape to secure it.  Do not let the wires touch each other, and do not use a stronger battery.  We then put the other  end of each wire into a glass with a solution of water and baking soda.  As soon as the wires were immersed we were able to observe the breaking down of water molecules into their atoms of hydrogen and oxygen.  As the students watched, the gases bubbled away from the ends of the wire and  we were able to discuss the concepts involved.  So, in this first phase we observed a molecule breaking down into atoms.

After a few minutes of observation the students began to observe another change.  The end of one of the wires was turning a bluish green.  Baking soda contains carbon atoms and when you combine hydrogen, oxygen, carbon, and copper (from the wires) you get hydroxycarbonate.  Hydroxycarbonate is that bluish green substance that we find on the Statue of Liberty which is made of copper.  In this phase of the experiment  we can watch as new molecules are formed.

Most science concepts can be taught with common household items…this one came from our textbook, love Dr. Wile, but there are experiments for just about everything online.

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