Topics include matter, elements, atoms, math and chemical reactions.
Content is geared toward the junior high level, but useful to anyone.
World Chemistry - This great site was created by the Leipzig International School in Germany and is aimed at advanced chemistry students in high school and college. The site includes some great tutorials and a glossary of over 200 chemistry terms. American Chemical Society - The world's largest scientific society, with a membership of over 155,000 chemists and chemical engineers. Includes science news and a job bank for members. Biomass - Good information about the process of turning plant chemical energy into electricity, heat, or liquid fuels.