Lyubov
Posts: 5
Joined: Fri Sep 14, 2007 11:16 am

### Model of Matter 6th grade

My son has to make physical 3-dimensional model of the molecules in matter. they want him to demonstrate the three states of matter and the motion and arrangement of the molecules in each of the three states. We have ideas about a stationary models ( wires, plastic balls). But how do you make a movable one? please help!

Craig_Bridge
Former Expert
Posts: 1297
Joined: Mon Oct 16, 2006 11:47 am

I'm confused by what a "model of a molecule" might be (grade level will help). At the high school chemistry grade level, models of molecules are decomposition models that show the atomic structure (e.g. what molecules are made of or are composed of).

In terms of gaseous, liquid, and solid states of molecules there are three common behaviors, those molecules that are unchanged as their form changes state, those that bend or fold or rotate on chemical bonds in their liquid and gaseous states, and those that break apart and are no longer the same chemical composition or molecule.

For example, if you melt most solid metals, the crystaline structure of the solid form no longer holds together and it enters a plastic state and then a liquid state but the individual molecules remain unchanged in terms of shape and size, they are just mobile. But this is just one class of molecules. For this class, a crystaline lattice model containing molecules is more appropriate than an atomic model.

There are whole fields of study devoted to these kinds of behaviors at the post doctorial level, but I'm guessing your son is in a lower grade and the challenge is to figure out what the teacher and/or book are really wanting.
-Craig

Craig_Bridge
Former Expert
Posts: 1297
Joined: Mon Oct 16, 2006 11:47 am
If the grade level is where "matter has three states, solid, liquid, and gas" is first being introduced, I recommend what I call "kitchen science".

Water (solid form ice, liquid form water, gaseous form steam) can be demonstrated by taking an ice cube from the freezer, putting it in a pan, heating it up, and boiling it.

Now, how do you model this? If you use some sort of balls to represent molecules, then the solid form requires attaching them solidly together (glue, toothpicks, something), the liquid form might be modeled by a bowl with them free to be mixed around, and the gaseous state is some clear sealed container with a several balls in it that can be shaken. Having balls that bounce off each other and the sides is probably about the best that you can do.

Showing either the model or the "kitchen science" demonstration by itself probably won't provide as much insite as doing both together and understanding the correlation between the model and the experiment.
-Craig

Craig_Bridge
Former Expert
Posts: 1297
Joined: Mon Oct 16, 2006 11:47 am
Forgot to mention that using a bowl or pitcher for the liquid state alows you to model pouring of the modeled liquid.
-Craig

Lyubov
Posts: 5
Joined: Fri Sep 14, 2007 11:16 am
Thank you very much, it helps a lot!