Science Buddies: "Ask an Expert"

I have melted my tin and bismuth and created crystals which turned out great. The only thing I am having trouble with is all the descriptions I get of a Tetragonal and Monoclinic Crystal structure. I really don't understand the definitions. All the stuff about Axes confuse me. Can someone give me an easy way to understand what each type of crystal would look like. Thank you very much.

The shape of a crystal can by very variable. For example, a monoclinic crystal may look different depending on how much room it has to grow, and other factors.

I might be able to provide some more concrete answers if you can describe the procedure you used to make your crystals (chemicals used, amounts, concentrations, etc.).

My son melted the bismuth/tin, allowed it to cool, poured off excess liquid bismuth/tin and had hardened crystals that remained. He first used 30 grams, then 57 grams, 70 grams, and 102 grams.

The definitions we have for the two crystals are as follows:

Monoclinic: Three unequal axes. The a and c crystallographic axes are inclined toward each other at an oblique angle, and the b axis is perpendicular to a and c. The b crystallographic axis is called the ortho axis.

Tetragonal: A simple cubic that is stretched along its c axis to form a rectangular prism. The tetragonal crystal will have a square base and top, but a height that is taller. By continuing to stretch the body centered cub on more bravais lattic of the tetragonal system is constructed.

We just don't understand what this is saying and are worried if Brady states all the above and gets asked what it means, he will look bad to the judges. I wish there was an easier way to say all that so he could understand it. I of course have no idea what it means. We have looked all over the internet for an easier description and can't find anything.

Thanks

This web page (below) might be a helpful source of information about crystal structures. The authors are very thorough and use every-day language. There are many example figures which your son could use in his presentations to help explain these complicated geometries.
http://www.rockhounds.com/rockshop/xtal ... html#index

Thanks for the great web page. It really helped explain and show how the crystals look. I can't believe in all our searching we never ran across this page. I am so glad Science Buddies is here to help! Thanks again!