Expert: Dr. Henry Boyter, Jr. - 7/24/2008

Question
I am teaching my 6-year-old some basics on the periodic table and how atoms make up molecules which make up everything. I am decorating a wall of his playroom with a periodic table and some simple molecules. I want to do things he'll recognize, so am using water, salt, etc. I want to do Fe2O3 (as an example of rust) but cannot find a single drawing of the structure online. I find I'm embarassingly mystified about how to arrange the atoms. Thank you for any help!

Answer
It is a little complicated.  Fe2O3 is a solid and so it exists in a crystal and the formula is the formula of the crystal lattice.  One drawing is given here.

http://en.wikipedia.org/wiki/Iron(III)_oxide

What it is, is a mix where if you count the whole thing out, the average is Fe2O3.  Really it is a Fe bonded to three Os.  Then each O is bonded to an Fe and so on for billions and billions of pairs.  Since each Fe is bonded to 3 Os that are also bonded to other Fe's, each O counts has 1/2 for each Fe (so 1.5O).  So it really is FeO1.5, but we round it up to Fe2O3.

It has the same structure of Al2O2.  This one is a little easier to see in the picture.

http://en.wikipedia.org/wiki/Aluminium_oxide

So for a simple model, it would be a Fe bonded to 3 O's, each of those Os bonded to a Fe, with two bonds sticking ut showing the structure continues to two other Os.  Then hang a picture of the structure from the structure.

For example, you could add the solid structure for NaCl to that one.  Emphasize these are SOLID structures.

http://en.wikipedia.org/wiki/Sodium_chloride


Good luck