From site:  MathMol (Mathematics and Molecules) is designed to serve as an introductory starting point for K-12 students and teachers interested in the field of molecular modeling and its application to mathematics.

Polymers, polymers, everywhere!  These activities, demos, lessons, and games help kids and teens learn all about polymers – how they’re made and what they’re used for.  Each of the rooms and levels in the “galleria” has different activities and polymer applications.  Learn why shrink wrap shrink, dashboards crack, and what those recycle numbers mean on plastic containers. 

From site:  The Physics Education Technology (PhET) project is an ongoing effort to provide an extensive suite of simulations for teaching and learning physics and chemistry and to make these resources both freely available from the PhET website and easy to incorporate into classrooms.

The simulations are animated, interactive, and game-like environments in which students learn through exploration. In these simulations, we emphasize the connections between real life phenomena and the underlying science and seek to make the visual and conceptual models that expert physicists use accessible to students.

This dynamic periodic table of elements lets you drill into specific elements to see what each does at specific temperatures, when they were added to the table, and their properties, orbitals and isotopes.  There’s even a link into Wikipedia that provides a popup with even more detailed information for each element.  The table can be printed for personal or classroom use.

The Periodic Table is an interactive website where students can learn about the Periodic Table of the Elements.  Explore how it is organized (into groups); the atomic structure of each group; characteristics of isotopes; the scientific notation that is used to define atoms and elements; and how the chemical properties of elements are determined by their atomic composition.