Friday, March 30, 2007
It's been quite a while since I've had to do a "class project". Oh, I've assisted with many and offered suggestions, glue and sticker letters for myriad projects in the past 20 years, beginning with a float for the "Storybook Parade" when Elizabeth was in preschool, and most recently, supplying a propeller for a "container project" in the shape of the Spirit of St. Louis, but a project by me, for me? It's been a while.
That's a water molecule. The arrows show the unequal sharing of the electrons in the covalent bond; the oxygen atom has more pull than the hydrogen atoms, resulting in a slightly negative charge at one end of the molecule and a slightly positive charge at the other. This is called a "polar molecule" and it's a main player in life on the planet earth. It has to do with why ice floats and why lakes freeze from the top down. It has an effect on what dissolves in water and what doesn't and it's a whole section of a chapter in high school chemistry. It was also my teaching subject for "class" last week.
That's the SECOND molecule I built. I knew in my mind what I wanted, and bought my styrofoam balls, sliced off sections to make flat surfaces, even got out my protractor to check the angle between the hydrogen atoms. Glued it all together with "model glue for plastics" and set it aside to dry.
HOW does plastic model glue work? Right...by dissolving a bit of the plastic and welding it to the next bit of plastic. It works really nicely on hard polystyrene. It works equally well on that styrofoam, except there isn't much plastic compared to the amount of air space in between. Rather to my astonishment, I picked up my model a few hours later and found large empty pockets where there used to be foam and glue. I had a 3-D model all right...a hollow one.
It was a bit flimsier than I had hoped, so I trekked back to the craft store, bought some more styrofoam balls and a bottle of tacky white glue and was glad that this was MY project and not a kid project at 10 PM on a Sunday night. The second molecule turned out just as I wanted and it gained me a bit of fame and glory at teacher class. Funny how everyone wants to touch the model and pass it around.
The best part wasn't the model, though. The best part was how much at home I felt in front of the group, teaching what I know.