Science Buddies: "Ask an Expert"

Plese anyone give me an idea!! I am a mom of a 5th grader and she has to make a 3-d model of an element we have chosen neon, she brought home next to nothing in the way of instructions. I am not a science expert and do not know how to help her start. She needs to make a 3-d model of her element, I have no idea what this would include! Any help would be much appreciated!!!

An atom is made up of three sub-atomic particles. Two of them are "big" or at least have most of the mass. These are the protons and neutrons. The huddle together in the center of the atom as the nucleus (thus the word for atom reactions and energy, "nuclear"). The other particles are electrons. The "float" or "orbit" around the nucleus in quantized energy levels or "shells", with higher energy "shells" being statistically further away from the nucleus.

So... a model of the atom can be constructued from styroform balls. Big ones for the protons and neutrons, small ones for the electrons. The big ones might be in two different colors to represent the two types. The big ones all get stuck together. Toothpicks will do the trick, or just plain glue them together. Since the protons all have a positive charge, they will try to space themselves away from one another, using the neutrons as "glue"... (actually there are other, really low mass particles that bounce around inside and help the neutrons and protons stick together... they are called appropriately, "gluons").

The electons can be connected to the nucleus by longer sticks, such as those wooden shishkabob skewers from the grocery store. Or, if a dynamic model, closer to the wild'n'wooly reality is desired... just glue them with string or even rubber bands cut to form rubber 'strings'... then model can be "jiggled" to represent the bouncing or "orbiting" electrons.

BTW... neon has ten protons, ten neutrons, and ten electrons:

http://www.chemicalelements.com/elements/ne.html

Good luck ! (My daughter graduated from high school in '04, but it was fun when she was in 5th grade.)

The posting by Candice is fine, but needs a little more information. The protron and neutron are rather small compared to the overall size of the atom. If you use styrofoam balls and toothpick and the balls were one inch in diameter, the overall atom with the cloud of electrons would be about the size of a house.

For a fifth grade project, the traditional sun-planet model is OK. Current theory puts the electrons in a lumpy cloud instead of a round orbit. Worry about that in college.

Robert Reavis

First of all, I agree that for the purpose of a 5th grade level project the styrofoam ball idea is the best way to go. Here is an alternate site with more information on Neon:

http://www.webelements.com/webelements/ ... e/key.html

As the previous posts point out, this model (like most models) does not accurately reflect nature. But you also want to consider what the context of the project is.

If the context is chemistry, for example, the interesting part of the atom are the electrons since their available energy states (the orbits in the planetary model) determine what kind of chemical bonds the Neon atom can have. In that spirit, using small styrofoam balls to depict the electrons is fine. But remember that we don't really know the size of an electron - for all we know, they are pointlike and we sometimes visualize them as zipping around the atom in some random fashion. Hence the idea of clouds of electrons shrouding the nucleus. I once saw a styrofoam model of a nucleus embedded in large amounts of cotton fluff. But again, if chemistry is the context, the electron energy levels are the important part and planetary orbits illustrate this information much better.

Now on the site I quote above, you can find information on the orbitals - these are not the orbits of the planetary model, but rather volumes centered on the nucleus in which you are most likely to find the electron. Their shapes and sizes depend on the electron's energy level and angular momentum.
The side also has numbers for the different radii you can attribute to Neon. No matter which one you choose, they give you a good idea of the dimensions you are dealing with. For example, it quotes the atomic radius at 38 picometers (roughly a billionth of an inch).
The atomic radius can be looked at as the size of the electron cloud averaged over all electrons at their lowest energy levels.
The radius of a proton is about 0.83 femtometers, roughly 20,000 times smaller than the atomic radius.
So if a proton is represented by a 1-inch diameter styrofoam ball, then the electron would be the size of the tip of a pin and flying around the styrofoam model in a volume 1666 feet across, about a third of a mile.
Obviously you can't build a model of those dimensions. But you can mention this kind of size comparison when presenting your model.

If the context is nuclear physics, the protons and neutrons are the more interesting part, and you want to be aware that they consist of even smaller particles (quarks and gluons). Now the actual sizes of the styrofoam balls really begin to matter more. If you dig deeper, you get into elementary particle physics, and it makes little sense to regard protons and neutrons as solid balls.