Explore the differences between chemical and physical changes, including some examples at the atomic level.

Created to teach students of the 21st century, SOPHIA is bringing matter straight to your fingertips. Become the commander of your own learning experiences as you take part in this interactive tutorial. [1:02]

Through a series of five related sections, this 24 page pdf file examines a range of topics associated with states of matter including physical interactions between molecular units, bonding within molecular units, molecular units of...

ChemCenter, available from the American Chemical Society, provides chemistry news, reference sources and other public services.

A collection of grid puzzles that cover a wide variety of topics in intermediate high school chemistry. These are excellent for topic review and reinforcement. The puzzles can be played online and also downloaded as worksheets. Answers...