Smell-O-Mints is an attractive and simple program for learning the Periodic Table of Elements.
It presents a basic table and a table with solids, liquids, and gasses. You don't even have to click on an element to get the corresponding information. Just pass the cursor over it, and the box in the lower left-hand corner displays the data that you need. The pop-up menu at the bottom lets you switch between the basic table and the solids, liquids, and gasses table.
For more information, including on later updates, please read the documentation or visit the home page.
Requirements are: Mac OS 8.6 or higher (Including Mac OS X), Carbon Lib 1.2 or higher, a PPC Mac and 5MB of RAM.